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

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commit 7bf9b7bef8 upstream.

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>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Al Viro 2012-12-16 00:25:57 +00:00 committed by Greg Kroah-Hartman
parent 99574fa03e
commit ebd3b1a320
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;