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x86/kprobes: Inline kprobe_exceptions_notify() into do_general_protection()

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The opaque plumbing of #GP from do_general_protection() through
notify_die() into kprobe_exceptions_notify() makes it hard to understand
what's going on.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: dvyukov@google.com
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20180828201421.157735-3-jannh@google.com
This commit is contained in:
Jann Horn 2018-08-28 22:14:16 +02:00 committed by Thomas Gleixner
parent a980c0ef9f
commit 76dee4a728
2 changed files with 11 additions and 30 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
arch/x86/kernel/kprobes/core.c
View file

@ -1028,42 +1028,13 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
if (fixup_exception(regs, trapnr))
return 1;
/*
* fixup routine could not handle it,
* Let do_page_fault() fix it.
*/
/* fixup routine could not handle it. */
}
return 0;
}
NOKPROBE_SYMBOL(kprobe_fault_handler);
/*
* Wrapper routine for handling exceptions.
*/
int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
void *data)
{
struct die_args *args = data;
int ret = NOTIFY_DONE;
if (args->regs && user_mode(args->regs))
return ret;
if (val == DIE_GPF) {
/*
* To be potentially processing a kprobe fault and to
* trust the result from kprobe_running(), we have
* be non-preemptible.
*/
if (!preemptible() && kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
}
return ret;
}
NOKPROBE_SYMBOL(kprobe_exceptions_notify);
bool arch_within_kprobe_blacklist(unsigned long addr)
{
bool is_in_entry_trampoline_section = false;

10
arch/x86/kernel/traps.c
View file

@ -556,6 +556,16 @@ do_general_protection(struct pt_regs *regs, long error_code)
tsk->thread.error_code = error_code;
tsk->thread.trap_nr = X86_TRAP_GP;
/*
* To be potentially processing a kprobe fault and to
* trust the result from kprobe_running(), we have to
* be non-preemptible.
*/
if (!preemptible() && kprobe_running() &&
kprobe_fault_handler(regs, X86_TRAP_GP))
return;
if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
die("general protection fault", regs, error_code);