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![Kees Cook](/assets/img/avatar_default.png)
This implements refcount_t overflow protection on x86 without a noticeable performance impact, though without the fuller checking of REFCOUNT_FULL. This is done by duplicating the existing atomic_t refcount implementation but with normally a single instruction added to detect if the refcount has gone negative (e.g. wrapped past INT_MAX or below zero). When detected, the handler saturates the refcount_t to INT_MIN / 2. With this overflow protection, the erroneous reference release that would follow a wrap back to zero is blocked from happening, avoiding the class of refcount-overflow use-after-free vulnerabilities entirely. Only the overflow case of refcounting can be perfectly protected, since it can be detected and stopped before the reference is freed and left to be abused by an attacker. There isn't a way to block early decrements, and while REFCOUNT_FULL stops increment-from-zero cases (which would be the state _after_ an early decrement and stops potential double-free conditions), this fast implementation does not, since it would require the more expensive cmpxchg loops. Since the overflow case is much more common (e.g. missing a "put" during an error path), this protection provides real-world protection. For example, the two public refcount overflow use-after-free exploits published in 2016 would have been rendered unexploitable: http://perception-point.io/2016/01/14/analysis-and-exploitation-of-a-linux-kernel-vulnerability-cve-2016-0728/ http://cyseclabs.com/page?n=02012016 This implementation does, however, notice an unchecked decrement to zero (i.e. caller used refcount_dec() instead of refcount_dec_and_test() and it resulted in a zero). Decrements under zero are noticed (since they will have resulted in a negative value), though this only indicates that a use-after-free may have already happened. Such notifications are likely avoidable by an attacker that has already exploited a use-after-free vulnerability, but it's better to have them reported than allow such conditions to remain universally silent. On first overflow detection, the refcount value is reset to INT_MIN / 2 (which serves as a saturation value) and a report and stack trace are produced. When operations detect only negative value results (such as changing an already saturated value), saturation still happens but no notification is performed (since the value was already saturated). On the matter of races, since the entire range beyond INT_MAX but before 0 is negative, every operation at INT_MIN / 2 will trap, leaving no overflow-only race condition. As for performance, this implementation adds a single "js" instruction to the regular execution flow of a copy of the standard atomic_t refcount operations. (The non-"and_test" refcount_dec() function, which is uncommon in regular refcount design patterns, has an additional "jz" instruction to detect reaching exactly zero.) Since this is a forward jump, it is by default the non-predicted path, which will be reinforced by dynamic branch prediction. The result is this protection having virtually no measurable change in performance over standard atomic_t operations. The error path, located in .text.unlikely, saves the refcount location and then uses UD0 to fire a refcount exception handler, which resets the refcount, handles reporting, and returns to regular execution. This keeps the changes to .text size minimal, avoiding return jumps and open-coded calls to the error reporting routine. Example assembly comparison: refcount_inc() before: .text: ffffffff81546149: f0 ff 45 f4 lock incl -0xc(%rbp) refcount_inc() after: .text: ffffffff81546149: f0 ff 45 f4 lock incl -0xc(%rbp) ffffffff8154614d: 0f 88 80 d5 17 00 js ffffffff816c36d3 ... .text.unlikely: ffffffff816c36d3: 48 8d 4d f4 lea -0xc(%rbp),%rcx ffffffff816c36d7: 0f ff (bad) These are the cycle counts comparing a loop of refcount_inc() from 1 to INT_MAX and back down to 0 (via refcount_dec_and_test()), between unprotected refcount_t (atomic_t), fully protected REFCOUNT_FULL (refcount_t-full), and this overflow-protected refcount (refcount_t-fast): 2147483646 refcount_inc()s and 2147483647 refcount_dec_and_test()s: cycles protections atomic_t 82249267387 none refcount_t-fast 82211446892 overflow, untested dec-to-zero refcount_t-full 144814735193 overflow, untested dec-to-zero, inc-from-zero This code is a modified version of the x86 PAX_REFCOUNT atomic_t overflow defense from the last public patch of PaX/grsecurity, based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Thanks to PaX Team for various suggestions for improvement for repurposing this code to be a refcount-only protection. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Hans Liljestrand <ishkamiel@gmail.com> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: Jann Horn <jannh@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Serge E. Hallyn <serge@hallyn.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: arozansk@redhat.com Cc: axboe@kernel.dk Cc: kernel-hardening@lists.openwall.com Cc: linux-arch <linux-arch@vger.kernel.org> Link: http://lkml.kernel.org/r/20170815161924.GA133115@beast Signed-off-by: Ingo Molnar <mingo@kernel.org>
629 lines
16 KiB
C
629 lines
16 KiB
C
/*
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* linux/kernel/panic.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* This function is used through-out the kernel (including mm and fs)
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* to indicate a major problem.
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*/
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#include <linux/debug_locks.h>
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#include <linux/sched/debug.h>
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#include <linux/interrupt.h>
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#include <linux/kmsg_dump.h>
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#include <linux/kallsyms.h>
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#include <linux/notifier.h>
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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/ftrace.h>
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#include <linux/reboot.h>
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#include <linux/delay.h>
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#include <linux/kexec.h>
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#include <linux/sched.h>
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#include <linux/sysrq.h>
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#include <linux/init.h>
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#include <linux/nmi.h>
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#include <linux/console.h>
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#include <linux/bug.h>
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#include <linux/ratelimit.h>
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#define PANIC_TIMER_STEP 100
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#define PANIC_BLINK_SPD 18
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int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
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static unsigned long tainted_mask;
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static int pause_on_oops;
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static int pause_on_oops_flag;
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static DEFINE_SPINLOCK(pause_on_oops_lock);
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bool crash_kexec_post_notifiers;
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int panic_on_warn __read_mostly;
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int panic_timeout = CONFIG_PANIC_TIMEOUT;
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EXPORT_SYMBOL_GPL(panic_timeout);
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ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
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EXPORT_SYMBOL(panic_notifier_list);
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static long no_blink(int state)
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{
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return 0;
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}
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/* Returns how long it waited in ms */
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long (*panic_blink)(int state);
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EXPORT_SYMBOL(panic_blink);
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/*
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* Stop ourself in panic -- architecture code may override this
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*/
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void __weak panic_smp_self_stop(void)
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{
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while (1)
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cpu_relax();
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}
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/*
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* Stop ourselves in NMI context if another CPU has already panicked. Arch code
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* may override this to prepare for crash dumping, e.g. save regs info.
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*/
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void __weak nmi_panic_self_stop(struct pt_regs *regs)
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{
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panic_smp_self_stop();
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}
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/*
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* Stop other CPUs in panic. Architecture dependent code may override this
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* with more suitable version. For example, if the architecture supports
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* crash dump, it should save registers of each stopped CPU and disable
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* per-CPU features such as virtualization extensions.
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*/
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void __weak crash_smp_send_stop(void)
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{
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static int cpus_stopped;
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/*
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* This function can be called twice in panic path, but obviously
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* we execute this only once.
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*/
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if (cpus_stopped)
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return;
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/*
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* Note smp_send_stop is the usual smp shutdown function, which
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* unfortunately means it may not be hardened to work in a panic
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* situation.
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*/
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smp_send_stop();
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cpus_stopped = 1;
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}
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atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID);
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/*
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* A variant of panic() called from NMI context. We return if we've already
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* panicked on this CPU. If another CPU already panicked, loop in
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* nmi_panic_self_stop() which can provide architecture dependent code such
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* as saving register state for crash dump.
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*/
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void nmi_panic(struct pt_regs *regs, const char *msg)
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{
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int old_cpu, cpu;
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cpu = raw_smp_processor_id();
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old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, cpu);
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if (old_cpu == PANIC_CPU_INVALID)
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panic("%s", msg);
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else if (old_cpu != cpu)
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nmi_panic_self_stop(regs);
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}
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EXPORT_SYMBOL(nmi_panic);
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/**
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* panic - halt the system
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* @fmt: The text string to print
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*
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* Display a message, then perform cleanups.
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*
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* This function never returns.
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*/
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void panic(const char *fmt, ...)
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{
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static char buf[1024];
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va_list args;
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long i, i_next = 0;
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int state = 0;
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int old_cpu, this_cpu;
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bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
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/*
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* Disable local interrupts. This will prevent panic_smp_self_stop
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* from deadlocking the first cpu that invokes the panic, since
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* there is nothing to prevent an interrupt handler (that runs
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* after setting panic_cpu) from invoking panic() again.
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*/
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local_irq_disable();
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/*
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* It's possible to come here directly from a panic-assertion and
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* not have preempt disabled. Some functions called from here want
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* preempt to be disabled. No point enabling it later though...
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*
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* Only one CPU is allowed to execute the panic code from here. For
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* multiple parallel invocations of panic, all other CPUs either
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* stop themself or will wait until they are stopped by the 1st CPU
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* with smp_send_stop().
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*
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* `old_cpu == PANIC_CPU_INVALID' means this is the 1st CPU which
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* comes here, so go ahead.
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* `old_cpu == this_cpu' means we came from nmi_panic() which sets
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* panic_cpu to this CPU. In this case, this is also the 1st CPU.
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*/
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this_cpu = raw_smp_processor_id();
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old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
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if (old_cpu != PANIC_CPU_INVALID && old_cpu != this_cpu)
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panic_smp_self_stop();
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console_verbose();
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bust_spinlocks(1);
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va_start(args, fmt);
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vsnprintf(buf, sizeof(buf), fmt, args);
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va_end(args);
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pr_emerg("Kernel panic - not syncing: %s\n", buf);
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#ifdef CONFIG_DEBUG_BUGVERBOSE
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/*
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* Avoid nested stack-dumping if a panic occurs during oops processing
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*/
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if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
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dump_stack();
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#endif
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/*
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* If we have crashed and we have a crash kernel loaded let it handle
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* everything else.
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* If we want to run this after calling panic_notifiers, pass
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* the "crash_kexec_post_notifiers" option to the kernel.
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*
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* Bypass the panic_cpu check and call __crash_kexec directly.
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*/
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if (!_crash_kexec_post_notifiers) {
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printk_safe_flush_on_panic();
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__crash_kexec(NULL);
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/*
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* Note smp_send_stop is the usual smp shutdown function, which
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* unfortunately means it may not be hardened to work in a
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* panic situation.
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*/
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smp_send_stop();
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} else {
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/*
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* If we want to do crash dump after notifier calls and
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* kmsg_dump, we will need architecture dependent extra
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* works in addition to stopping other CPUs.
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*/
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crash_smp_send_stop();
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}
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/*
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* Run any panic handlers, including those that might need to
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* add information to the kmsg dump output.
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*/
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atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
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/* Call flush even twice. It tries harder with a single online CPU */
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printk_safe_flush_on_panic();
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kmsg_dump(KMSG_DUMP_PANIC);
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/*
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* If you doubt kdump always works fine in any situation,
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* "crash_kexec_post_notifiers" offers you a chance to run
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* panic_notifiers and dumping kmsg before kdump.
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* Note: since some panic_notifiers can make crashed kernel
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* more unstable, it can increase risks of the kdump failure too.
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*
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* Bypass the panic_cpu check and call __crash_kexec directly.
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*/
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if (_crash_kexec_post_notifiers)
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__crash_kexec(NULL);
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bust_spinlocks(0);
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/*
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* We may have ended up stopping the CPU holding the lock (in
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* smp_send_stop()) while still having some valuable data in the console
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* buffer. Try to acquire the lock then release it regardless of the
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* result. The release will also print the buffers out. Locks debug
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* should be disabled to avoid reporting bad unlock balance when
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* panic() is not being callled from OOPS.
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*/
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debug_locks_off();
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console_flush_on_panic();
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if (!panic_blink)
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panic_blink = no_blink;
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if (panic_timeout > 0) {
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/*
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* Delay timeout seconds before rebooting the machine.
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* We can't use the "normal" timers since we just panicked.
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*/
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pr_emerg("Rebooting in %d seconds..\n", panic_timeout);
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for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
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touch_nmi_watchdog();
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if (i >= i_next) {
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i += panic_blink(state ^= 1);
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i_next = i + 3600 / PANIC_BLINK_SPD;
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}
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mdelay(PANIC_TIMER_STEP);
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}
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}
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if (panic_timeout != 0) {
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/*
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* This will not be a clean reboot, with everything
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* shutting down. But if there is a chance of
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* rebooting the system it will be rebooted.
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*/
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emergency_restart();
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}
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#ifdef __sparc__
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{
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extern int stop_a_enabled;
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/* Make sure the user can actually press Stop-A (L1-A) */
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stop_a_enabled = 1;
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pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
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"twice on console to return to the boot prom\n");
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}
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#endif
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#if defined(CONFIG_S390)
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{
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unsigned long caller;
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caller = (unsigned long)__builtin_return_address(0);
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disabled_wait(caller);
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}
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#endif
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pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
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local_irq_enable();
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for (i = 0; ; i += PANIC_TIMER_STEP) {
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touch_softlockup_watchdog();
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if (i >= i_next) {
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i += panic_blink(state ^= 1);
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i_next = i + 3600 / PANIC_BLINK_SPD;
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}
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mdelay(PANIC_TIMER_STEP);
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}
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}
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EXPORT_SYMBOL(panic);
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/*
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* TAINT_FORCED_RMMOD could be a per-module flag but the module
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* is being removed anyway.
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*/
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const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
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{ 'P', 'G', true }, /* TAINT_PROPRIETARY_MODULE */
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{ 'F', ' ', true }, /* TAINT_FORCED_MODULE */
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{ 'S', ' ', false }, /* TAINT_CPU_OUT_OF_SPEC */
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{ 'R', ' ', false }, /* TAINT_FORCED_RMMOD */
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{ 'M', ' ', false }, /* TAINT_MACHINE_CHECK */
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{ 'B', ' ', false }, /* TAINT_BAD_PAGE */
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{ 'U', ' ', false }, /* TAINT_USER */
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{ 'D', ' ', false }, /* TAINT_DIE */
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{ 'A', ' ', false }, /* TAINT_OVERRIDDEN_ACPI_TABLE */
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{ 'W', ' ', false }, /* TAINT_WARN */
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{ 'C', ' ', true }, /* TAINT_CRAP */
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{ 'I', ' ', false }, /* TAINT_FIRMWARE_WORKAROUND */
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{ 'O', ' ', true }, /* TAINT_OOT_MODULE */
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{ 'E', ' ', true }, /* TAINT_UNSIGNED_MODULE */
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{ 'L', ' ', false }, /* TAINT_SOFTLOCKUP */
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{ 'K', ' ', true }, /* TAINT_LIVEPATCH */
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};
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/**
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* print_tainted - return a string to represent the kernel taint state.
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*
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* 'P' - Proprietary module has been loaded.
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* 'F' - Module has been forcibly loaded.
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* 'S' - SMP with CPUs not designed for SMP.
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* 'R' - User forced a module unload.
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* 'M' - System experienced a machine check exception.
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* 'B' - System has hit bad_page.
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* 'U' - Userspace-defined naughtiness.
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* 'D' - Kernel has oopsed before
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* 'A' - ACPI table overridden.
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* 'W' - Taint on warning.
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* 'C' - modules from drivers/staging are loaded.
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* 'I' - Working around severe firmware bug.
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* 'O' - Out-of-tree module has been loaded.
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* 'E' - Unsigned module has been loaded.
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* 'L' - A soft lockup has previously occurred.
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* 'K' - Kernel has been live patched.
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*
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* The string is overwritten by the next call to print_tainted().
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*/
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const char *print_tainted(void)
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{
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static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
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if (tainted_mask) {
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char *s;
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int i;
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s = buf + sprintf(buf, "Tainted: ");
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for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
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const struct taint_flag *t = &taint_flags[i];
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*s++ = test_bit(i, &tainted_mask) ?
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t->c_true : t->c_false;
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}
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*s = 0;
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} else
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snprintf(buf, sizeof(buf), "Not tainted");
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return buf;
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}
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int test_taint(unsigned flag)
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{
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return test_bit(flag, &tainted_mask);
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}
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EXPORT_SYMBOL(test_taint);
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unsigned long get_taint(void)
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{
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return tainted_mask;
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}
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/**
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* add_taint: add a taint flag if not already set.
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* @flag: one of the TAINT_* constants.
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* @lockdep_ok: whether lock debugging is still OK.
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*
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* If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
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* some notewortht-but-not-corrupting cases, it can be set to true.
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*/
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void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
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{
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if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
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pr_warn("Disabling lock debugging due to kernel taint\n");
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set_bit(flag, &tainted_mask);
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}
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EXPORT_SYMBOL(add_taint);
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static void spin_msec(int msecs)
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{
|
|
int i;
|
|
|
|
for (i = 0; i < msecs; i++) {
|
|
touch_nmi_watchdog();
|
|
mdelay(1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* It just happens that oops_enter() and oops_exit() are identically
|
|
* implemented...
|
|
*/
|
|
static void do_oops_enter_exit(void)
|
|
{
|
|
unsigned long flags;
|
|
static int spin_counter;
|
|
|
|
if (!pause_on_oops)
|
|
return;
|
|
|
|
spin_lock_irqsave(&pause_on_oops_lock, flags);
|
|
if (pause_on_oops_flag == 0) {
|
|
/* This CPU may now print the oops message */
|
|
pause_on_oops_flag = 1;
|
|
} else {
|
|
/* We need to stall this CPU */
|
|
if (!spin_counter) {
|
|
/* This CPU gets to do the counting */
|
|
spin_counter = pause_on_oops;
|
|
do {
|
|
spin_unlock(&pause_on_oops_lock);
|
|
spin_msec(MSEC_PER_SEC);
|
|
spin_lock(&pause_on_oops_lock);
|
|
} while (--spin_counter);
|
|
pause_on_oops_flag = 0;
|
|
} else {
|
|
/* This CPU waits for a different one */
|
|
while (spin_counter) {
|
|
spin_unlock(&pause_on_oops_lock);
|
|
spin_msec(1);
|
|
spin_lock(&pause_on_oops_lock);
|
|
}
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&pause_on_oops_lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Return true if the calling CPU is allowed to print oops-related info.
|
|
* This is a bit racy..
|
|
*/
|
|
int oops_may_print(void)
|
|
{
|
|
return pause_on_oops_flag == 0;
|
|
}
|
|
|
|
/*
|
|
* Called when the architecture enters its oops handler, before it prints
|
|
* anything. If this is the first CPU to oops, and it's oopsing the first
|
|
* time then let it proceed.
|
|
*
|
|
* This is all enabled by the pause_on_oops kernel boot option. We do all
|
|
* this to ensure that oopses don't scroll off the screen. It has the
|
|
* side-effect of preventing later-oopsing CPUs from mucking up the display,
|
|
* too.
|
|
*
|
|
* It turns out that the CPU which is allowed to print ends up pausing for
|
|
* the right duration, whereas all the other CPUs pause for twice as long:
|
|
* once in oops_enter(), once in oops_exit().
|
|
*/
|
|
void oops_enter(void)
|
|
{
|
|
tracing_off();
|
|
/* can't trust the integrity of the kernel anymore: */
|
|
debug_locks_off();
|
|
do_oops_enter_exit();
|
|
}
|
|
|
|
/*
|
|
* 64-bit random ID for oopses:
|
|
*/
|
|
static u64 oops_id;
|
|
|
|
static int init_oops_id(void)
|
|
{
|
|
if (!oops_id)
|
|
get_random_bytes(&oops_id, sizeof(oops_id));
|
|
else
|
|
oops_id++;
|
|
|
|
return 0;
|
|
}
|
|
late_initcall(init_oops_id);
|
|
|
|
void print_oops_end_marker(void)
|
|
{
|
|
init_oops_id();
|
|
pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
|
|
}
|
|
|
|
/*
|
|
* Called when the architecture exits its oops handler, after printing
|
|
* everything.
|
|
*/
|
|
void oops_exit(void)
|
|
{
|
|
do_oops_enter_exit();
|
|
print_oops_end_marker();
|
|
kmsg_dump(KMSG_DUMP_OOPS);
|
|
}
|
|
|
|
struct warn_args {
|
|
const char *fmt;
|
|
va_list args;
|
|
};
|
|
|
|
void __warn(const char *file, int line, void *caller, unsigned taint,
|
|
struct pt_regs *regs, struct warn_args *args)
|
|
{
|
|
disable_trace_on_warning();
|
|
|
|
pr_warn("------------[ cut here ]------------\n");
|
|
|
|
if (file)
|
|
pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
|
|
raw_smp_processor_id(), current->pid, file, line,
|
|
caller);
|
|
else
|
|
pr_warn("WARNING: CPU: %d PID: %d at %pS\n",
|
|
raw_smp_processor_id(), current->pid, caller);
|
|
|
|
if (args)
|
|
vprintk(args->fmt, args->args);
|
|
|
|
if (panic_on_warn) {
|
|
/*
|
|
* This thread may hit another WARN() in the panic path.
|
|
* Resetting this prevents additional WARN() from panicking the
|
|
* system on this thread. Other threads are blocked by the
|
|
* panic_mutex in panic().
|
|
*/
|
|
panic_on_warn = 0;
|
|
panic("panic_on_warn set ...\n");
|
|
}
|
|
|
|
print_modules();
|
|
|
|
if (regs)
|
|
show_regs(regs);
|
|
else
|
|
dump_stack();
|
|
|
|
print_oops_end_marker();
|
|
|
|
/* Just a warning, don't kill lockdep. */
|
|
add_taint(taint, LOCKDEP_STILL_OK);
|
|
}
|
|
|
|
#ifdef WANT_WARN_ON_SLOWPATH
|
|
void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
|
|
{
|
|
struct warn_args args;
|
|
|
|
args.fmt = fmt;
|
|
va_start(args.args, fmt);
|
|
__warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL,
|
|
&args);
|
|
va_end(args.args);
|
|
}
|
|
EXPORT_SYMBOL(warn_slowpath_fmt);
|
|
|
|
void warn_slowpath_fmt_taint(const char *file, int line,
|
|
unsigned taint, const char *fmt, ...)
|
|
{
|
|
struct warn_args args;
|
|
|
|
args.fmt = fmt;
|
|
va_start(args.args, fmt);
|
|
__warn(file, line, __builtin_return_address(0), taint, NULL, &args);
|
|
va_end(args.args);
|
|
}
|
|
EXPORT_SYMBOL(warn_slowpath_fmt_taint);
|
|
|
|
void warn_slowpath_null(const char *file, int line)
|
|
{
|
|
__warn(file, line, __builtin_return_address(0), TAINT_WARN, NULL, NULL);
|
|
}
|
|
EXPORT_SYMBOL(warn_slowpath_null);
|
|
#endif
|
|
|
|
#ifdef CONFIG_CC_STACKPROTECTOR
|
|
|
|
/*
|
|
* Called when gcc's -fstack-protector feature is used, and
|
|
* gcc detects corruption of the on-stack canary value
|
|
*/
|
|
__visible void __stack_chk_fail(void)
|
|
{
|
|
panic("stack-protector: Kernel stack is corrupted in: %p\n",
|
|
__builtin_return_address(0));
|
|
}
|
|
EXPORT_SYMBOL(__stack_chk_fail);
|
|
|
|
#endif
|
|
|
|
#ifdef CONFIG_ARCH_HAS_REFCOUNT
|
|
void refcount_error_report(struct pt_regs *regs, const char *err)
|
|
{
|
|
WARN_RATELIMIT(1, "refcount_t %s at %pB in %s[%d], uid/euid: %u/%u\n",
|
|
err, (void *)instruction_pointer(regs),
|
|
current->comm, task_pid_nr(current),
|
|
from_kuid_munged(&init_user_ns, current_uid()),
|
|
from_kuid_munged(&init_user_ns, current_euid()));
|
|
}
|
|
#endif
|
|
|
|
core_param(panic, panic_timeout, int, 0644);
|
|
core_param(pause_on_oops, pause_on_oops, int, 0644);
|
|
core_param(panic_on_warn, panic_on_warn, int, 0644);
|
|
core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
|
|
|
|
static int __init oops_setup(char *s)
|
|
{
|
|
if (!s)
|
|
return -EINVAL;
|
|
if (!strcmp(s, "panic"))
|
|
panic_on_oops = 1;
|
|
return 0;
|
|
}
|
|
early_param("oops", oops_setup);
|