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x86: don't send SIGBUS for kernel page faults

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It's wrong for several reasons, but the most direct one is that the
fault may be for the stack accesses to set up a previous SIGBUS.  When
we have a kernel exception, the kernel exception handler does all the
fixups, not some user-level signal handler.

Even apart from the nested SIGBUS issue, it's also wrong to give out
kernel fault addresses in the signal handler info block, or to send a
SIGBUS when a system call already returns EFAULT.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2010-08-13 09:49:20 -07:00
parent 5528f9132c
commit 9605456919
1 changed files with 3 additions and 1 deletions
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4
arch/x86/mm/fault.c
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@@ -802,8 +802,10 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address,
up_read(&mm->mmap_sem); up_read(&mm->mmap_sem);
/* Kernel mode? Handle exceptions or die: */ /* Kernel mode? Handle exceptions or die: */
if (!(error_code & PF_USER)) if (!(error_code & PF_USER)) {
no_context(regs, error_code, address); no_context(regs, error_code, address);
return;
}
/* User-space => ok to do another page fault: */ /* User-space => ok to do another page fault: */
if (is_prefetch(regs, error_code, address)) if (is_prefetch(regs, error_code, address))