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ARM: Ensure do_cache_op takes mmap_sem
author
Russell King
<rmk+kernel@arm.linux.org.uk>
Mon, 28 Sep 2009 10:41:51 +0000
(11:41 +0100)
committer
Russell King
<rmk+kernel@arm.linux.org.uk>
Mon, 28 Sep 2009 17:06:21 +0000
(18:06 +0100)
do_cache_op() uses find_vma() to validate its arguments without holding
any locking. This means that the VMA could vanish beneath us. Fix
this by taking a read lock on mmap_sem.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
arch/arm/kernel/traps.c
patch
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diff --git
a/arch/arm/kernel/traps.c
b/arch/arm/kernel/traps.c
index
57eb0f6
..
467b69e
100644
(file)
--- a/
arch/arm/kernel/traps.c
+++ b/
arch/arm/kernel/traps.c
@@
-418,12
+418,14
@@
static int bad_syscall(int n, struct pt_regs *regs)
static inline void
do_cache_op(unsigned long start, unsigned long end, int flags)
{
+ struct mm_struct *mm = current->active_mm;
struct vm_area_struct *vma;
if (end < start || flags)
return;
- vma = find_vma(current->active_mm, start);
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, start);
if (vma && vma->vm_start < end) {
if (start < vma->vm_start)
start = vma->vm_start;
@@
-432,6
+434,7
@@
do_cache_op(unsigned long start, unsigned long end, int flags)
flush_cache_user_range(vma, start, end);
}
+ up_read(&mm->mmap_sem);
}
/*