mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
Pull force_sig() argument change from Eric Biederman: "A source of error over the years has been that force_sig has taken a task parameter when it is only safe to use force_sig with the current task. The force_sig function is built for delivering synchronous signals such as SIGSEGV where the userspace application caused a synchronous fault (such as a page fault) and the kernel responded with a signal. Because the name force_sig does not make this clear, and because the force_sig takes a task parameter the function force_sig has been abused for sending other kinds of signals over the years. Slowly those have been fixed when the oopses have been tracked down. This set of changes fixes the remaining abusers of force_sig and carefully rips out the task parameter from force_sig and friends making this kind of error almost impossible in the future" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits) signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus signal: Remove the signal number and task parameters from force_sig_info signal: Factor force_sig_info_to_task out of force_sig_info signal: Generate the siginfo in force_sig signal: Move the computation of force into send_signal and correct it. signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal signal: Remove the task parameter from force_sig_fault signal: Use force_sig_fault_to_task for the two calls that don't deliver to current signal: Explicitly call force_sig_fault on current signal/unicore32: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from __do_user_fault signal/arm: Remove tsk parameter from ptrace_break signal/nds32: Remove tsk parameter from send_sigtrap signal/riscv: Remove tsk parameter from do_trap signal/sh: Remove tsk parameter from force_sig_info_fault signal/um: Remove task parameter from send_sigtrap signal/x86: Remove task parameter from send_sigtrap signal: Remove task parameter from force_sig_mceerr signal: Remove task parameter from force_sig signal: Remove task parameter from force_sigsegv ...
350 lines
8.5 KiB
C
350 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* OpenRISC fault.c
|
|
*
|
|
* Linux architectural port borrowing liberally from similar works of
|
|
* others. All original copyrights apply as per the original source
|
|
* declaration.
|
|
*
|
|
* Modifications for the OpenRISC architecture:
|
|
* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
|
|
* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
|
|
*/
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/extable.h>
|
|
#include <linux/sched/signal.h>
|
|
|
|
#include <linux/uaccess.h>
|
|
#include <asm/siginfo.h>
|
|
#include <asm/signal.h>
|
|
|
|
#define NUM_TLB_ENTRIES 64
|
|
#define TLB_OFFSET(add) (((add) >> PAGE_SHIFT) & (NUM_TLB_ENTRIES-1))
|
|
|
|
unsigned long pte_misses; /* updated by do_page_fault() */
|
|
unsigned long pte_errors; /* updated by do_page_fault() */
|
|
|
|
/* __PHX__ :: - check the vmalloc_fault in do_page_fault()
|
|
* - also look into include/asm-or32/mmu_context.h
|
|
*/
|
|
volatile pgd_t *current_pgd[NR_CPUS];
|
|
|
|
extern void die(char *, struct pt_regs *, long);
|
|
|
|
/*
|
|
* This routine handles page faults. It determines the address,
|
|
* and the problem, and then passes it off to one of the appropriate
|
|
* routines.
|
|
*
|
|
* If this routine detects a bad access, it returns 1, otherwise it
|
|
* returns 0.
|
|
*/
|
|
|
|
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
|
|
unsigned long vector, int write_acc)
|
|
{
|
|
struct task_struct *tsk;
|
|
struct mm_struct *mm;
|
|
struct vm_area_struct *vma;
|
|
int si_code;
|
|
vm_fault_t fault;
|
|
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
|
|
|
|
tsk = current;
|
|
|
|
/*
|
|
* We fault-in kernel-space virtual memory on-demand. The
|
|
* 'reference' page table is init_mm.pgd.
|
|
*
|
|
* NOTE! We MUST NOT take any locks for this case. We may
|
|
* be in an interrupt or a critical region, and should
|
|
* only copy the information from the master page table,
|
|
* nothing more.
|
|
*
|
|
* NOTE2: This is done so that, when updating the vmalloc
|
|
* mappings we don't have to walk all processes pgdirs and
|
|
* add the high mappings all at once. Instead we do it as they
|
|
* are used. However vmalloc'ed page entries have the PAGE_GLOBAL
|
|
* bit set so sometimes the TLB can use a lingering entry.
|
|
*
|
|
* This verifies that the fault happens in kernel space
|
|
* and that the fault was not a protection error.
|
|
*/
|
|
|
|
if (address >= VMALLOC_START &&
|
|
(vector != 0x300 && vector != 0x400) &&
|
|
!user_mode(regs))
|
|
goto vmalloc_fault;
|
|
|
|
/* If exceptions were enabled, we can reenable them here */
|
|
if (user_mode(regs)) {
|
|
/* Exception was in userspace: reenable interrupts */
|
|
local_irq_enable();
|
|
flags |= FAULT_FLAG_USER;
|
|
} else {
|
|
/* If exception was in a syscall, then IRQ's may have
|
|
* been enabled or disabled. If they were enabled,
|
|
* reenable them.
|
|
*/
|
|
if (regs->sr && (SPR_SR_IEE | SPR_SR_TEE))
|
|
local_irq_enable();
|
|
}
|
|
|
|
mm = tsk->mm;
|
|
si_code = SEGV_MAPERR;
|
|
|
|
/*
|
|
* If we're in an interrupt or have no user
|
|
* context, we must not take the fault..
|
|
*/
|
|
|
|
if (in_interrupt() || !mm)
|
|
goto no_context;
|
|
|
|
retry:
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, address);
|
|
|
|
if (!vma)
|
|
goto bad_area;
|
|
|
|
if (vma->vm_start <= address)
|
|
goto good_area;
|
|
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
goto bad_area;
|
|
|
|
if (user_mode(regs)) {
|
|
/*
|
|
* accessing the stack below usp is always a bug.
|
|
* we get page-aligned addresses so we can only check
|
|
* if we're within a page from usp, but that might be
|
|
* enough to catch brutal errors at least.
|
|
*/
|
|
if (address + PAGE_SIZE < regs->sp)
|
|
goto bad_area;
|
|
}
|
|
if (expand_stack(vma, address))
|
|
goto bad_area;
|
|
|
|
/*
|
|
* Ok, we have a good vm_area for this memory access, so
|
|
* we can handle it..
|
|
*/
|
|
|
|
good_area:
|
|
si_code = SEGV_ACCERR;
|
|
|
|
/* first do some preliminary protection checks */
|
|
|
|
if (write_acc) {
|
|
if (!(vma->vm_flags & VM_WRITE))
|
|
goto bad_area;
|
|
flags |= FAULT_FLAG_WRITE;
|
|
} else {
|
|
/* not present */
|
|
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
|
|
goto bad_area;
|
|
}
|
|
|
|
/* are we trying to execute nonexecutable area */
|
|
if ((vector == 0x400) && !(vma->vm_page_prot.pgprot & _PAGE_EXEC))
|
|
goto bad_area;
|
|
|
|
/*
|
|
* If for any reason at all we couldn't handle the fault,
|
|
* make sure we exit gracefully rather than endlessly redo
|
|
* the fault.
|
|
*/
|
|
|
|
fault = handle_mm_fault(vma, address, flags);
|
|
|
|
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
|
|
return;
|
|
|
|
if (unlikely(fault & VM_FAULT_ERROR)) {
|
|
if (fault & VM_FAULT_OOM)
|
|
goto out_of_memory;
|
|
else if (fault & VM_FAULT_SIGSEGV)
|
|
goto bad_area;
|
|
else if (fault & VM_FAULT_SIGBUS)
|
|
goto do_sigbus;
|
|
BUG();
|
|
}
|
|
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
/*RGD modeled on Cris */
|
|
if (fault & VM_FAULT_MAJOR)
|
|
tsk->maj_flt++;
|
|
else
|
|
tsk->min_flt++;
|
|
if (fault & VM_FAULT_RETRY) {
|
|
flags &= ~FAULT_FLAG_ALLOW_RETRY;
|
|
flags |= FAULT_FLAG_TRIED;
|
|
|
|
/* No need to up_read(&mm->mmap_sem) as we would
|
|
* have already released it in __lock_page_or_retry
|
|
* in mm/filemap.c.
|
|
*/
|
|
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
up_read(&mm->mmap_sem);
|
|
return;
|
|
|
|
/*
|
|
* Something tried to access memory that isn't in our memory map..
|
|
* Fix it, but check if it's kernel or user first..
|
|
*/
|
|
|
|
bad_area:
|
|
up_read(&mm->mmap_sem);
|
|
|
|
bad_area_nosemaphore:
|
|
|
|
/* User mode accesses just cause a SIGSEGV */
|
|
|
|
if (user_mode(regs)) {
|
|
force_sig_fault(SIGSEGV, si_code, (void __user *)address);
|
|
return;
|
|
}
|
|
|
|
no_context:
|
|
|
|
/* Are we prepared to handle this kernel fault?
|
|
*
|
|
* (The kernel has valid exception-points in the source
|
|
* when it acesses user-memory. When it fails in one
|
|
* of those points, we find it in a table and do a jump
|
|
* to some fixup code that loads an appropriate error
|
|
* code)
|
|
*/
|
|
|
|
{
|
|
const struct exception_table_entry *entry;
|
|
|
|
__asm__ __volatile__("l.nop 42");
|
|
|
|
if ((entry = search_exception_tables(regs->pc)) != NULL) {
|
|
/* Adjust the instruction pointer in the stackframe */
|
|
regs->pc = entry->fixup;
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Oops. The kernel tried to access some bad page. We'll have to
|
|
* terminate things with extreme prejudice.
|
|
*/
|
|
|
|
if ((unsigned long)(address) < PAGE_SIZE)
|
|
printk(KERN_ALERT
|
|
"Unable to handle kernel NULL pointer dereference");
|
|
else
|
|
printk(KERN_ALERT "Unable to handle kernel access");
|
|
printk(" at virtual address 0x%08lx\n", address);
|
|
|
|
die("Oops", regs, write_acc);
|
|
|
|
do_exit(SIGKILL);
|
|
|
|
/*
|
|
* We ran out of memory, or some other thing happened to us that made
|
|
* us unable to handle the page fault gracefully.
|
|
*/
|
|
|
|
out_of_memory:
|
|
__asm__ __volatile__("l.nop 42");
|
|
__asm__ __volatile__("l.nop 1");
|
|
|
|
up_read(&mm->mmap_sem);
|
|
if (!user_mode(regs))
|
|
goto no_context;
|
|
pagefault_out_of_memory();
|
|
return;
|
|
|
|
do_sigbus:
|
|
up_read(&mm->mmap_sem);
|
|
|
|
/*
|
|
* Send a sigbus, regardless of whether we were in kernel
|
|
* or user mode.
|
|
*/
|
|
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
|
|
|
|
/* Kernel mode? Handle exceptions or die */
|
|
if (!user_mode(regs))
|
|
goto no_context;
|
|
return;
|
|
|
|
vmalloc_fault:
|
|
{
|
|
/*
|
|
* Synchronize this task's top level page-table
|
|
* with the 'reference' page table.
|
|
*
|
|
* Use current_pgd instead of tsk->active_mm->pgd
|
|
* since the latter might be unavailable if this
|
|
* code is executed in a misfortunately run irq
|
|
* (like inside schedule() between switch_mm and
|
|
* switch_to...).
|
|
*/
|
|
|
|
int offset = pgd_index(address);
|
|
pgd_t *pgd, *pgd_k;
|
|
pud_t *pud, *pud_k;
|
|
pmd_t *pmd, *pmd_k;
|
|
pte_t *pte_k;
|
|
|
|
/*
|
|
phx_warn("do_page_fault(): vmalloc_fault will not work, "
|
|
"since current_pgd assign a proper value somewhere\n"
|
|
"anyhow we don't need this at the moment\n");
|
|
|
|
phx_mmu("vmalloc_fault");
|
|
*/
|
|
pgd = (pgd_t *)current_pgd[smp_processor_id()] + offset;
|
|
pgd_k = init_mm.pgd + offset;
|
|
|
|
/* Since we're two-level, we don't need to do both
|
|
* set_pgd and set_pmd (they do the same thing). If
|
|
* we go three-level at some point, do the right thing
|
|
* with pgd_present and set_pgd here.
|
|
*
|
|
* Also, since the vmalloc area is global, we don't
|
|
* need to copy individual PTE's, it is enough to
|
|
* copy the pgd pointer into the pte page of the
|
|
* root task. If that is there, we'll find our pte if
|
|
* it exists.
|
|
*/
|
|
|
|
pud = pud_offset(pgd, address);
|
|
pud_k = pud_offset(pgd_k, address);
|
|
if (!pud_present(*pud_k))
|
|
goto no_context;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
pmd_k = pmd_offset(pud_k, address);
|
|
|
|
if (!pmd_present(*pmd_k))
|
|
goto bad_area_nosemaphore;
|
|
|
|
set_pmd(pmd, *pmd_k);
|
|
|
|
/* Make sure the actual PTE exists as well to
|
|
* catch kernel vmalloc-area accesses to non-mapped
|
|
* addresses. If we don't do this, this will just
|
|
* silently loop forever.
|
|
*/
|
|
|
|
pte_k = pte_offset_kernel(pmd_k, address);
|
|
if (!pte_present(*pte_k))
|
|
goto no_context;
|
|
|
|
return;
|
|
}
|
|
}
|