Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 38/47] ARM: missing ->mmap_sem around find_vma() in swp_emulate.c | Date | Wed, 9 Jan 2013 12:35:33 -0800 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro <viro@ZenIV.linux.org.uk>
commit 7bf9b7bef881aac820bf1f2e9951a17b09bd7e04 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>
--- arch/arm/kernel/swp_emulate.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/arch/arm/kernel/swp_emulate.c +++ b/arch/arm/kernel/swp_emulate.c @@ -108,10 +108,12 @@ static void set_segfault(struct pt_regs { siginfo_t info; + down_read(¤t->mm->mmap_sem); if (find_vma(current->mm, addr) == NULL) info.si_code = SEGV_MAPERR; else info.si_code = SEGV_ACCERR; + up_read(¤t->mm->mmap_sem); info.si_signo = SIGSEGV; info.si_errno = 0;
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