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ARM: missing ->mmap_sem around find_vma() in swp_emulate.c

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find_vma() is *not* safe when somebody else is removing vmas.  Not just
the return value might get bogus just as you are getting it (this instance
doesn't try to dereference the resulting vma), the search itself can get
buggered in rather spectacular ways.  IOW, ->mmap_sem really, really is
not optional here.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Al Viro 2012-12-16 00:25:57 +00:00 committed by Russell King
parent dad5451a32
commit 7bf9b7bef8
1 changed files with 2 additions and 0 deletions
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2
arch/arm/kernel/swp_emulate.c
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@ -109,10 +109,12 @@ static void set_segfault(struct pt_regs *regs, unsigned long addr)
{
siginfo_t info;
down_read(&current->mm->mmap_sem);
if (find_vma(current->mm, addr) == NULL)
info.si_code = SEGV_MAPERR;
else
info.si_code = SEGV_ACCERR;
up_read(&current->mm->mmap_sem);
info.si_signo = SIGSEGV;
info.si_errno = 0;