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authorAl Viro <viro@ZenIV.linux.org.uk>2012-12-16 00:25:57 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-12-20 10:40:24 +0000
commit7bf9b7bef881aac820bf1f2e9951a17b09bd7e04 (patch)
tree6c74611883e16e5cd6548f9dd3278a9f2fadb1e3
parentdad5451a322bb682704f3ab13a558508a83e0b93 (diff)
ARM: missing ->mmap_sem around find_vma() in swp_emulate.c
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>
-rw-r--r--arch/arm/kernel/swp_emulate.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
index df745188f5de..ab1017bd1667 100644
--- a/arch/arm/kernel/swp_emulate.c
+++ b/arch/arm/kernel/swp_emulate.c
@@ -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;