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authorRussell King <rmk+kernel@arm.linux.org.uk>2009-09-28 11:41:51 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-09-28 18:06:21 +0100
commitaa45ee8fc0ee87c1711b5fe8eb3556d06530c39e (patch)
tree4fd5a65dd1dda67ba8e2c4857bf1c7f5c19edaf8
parent90140c30a7b8c77e8872a389d48678d78e58789f (diff)
ARM: Ensure do_cache_op takes mmap_sem
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>
-rw-r--r--arch/arm/kernel/traps.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 57eb0f6f600..467b69ed102 100644
--- 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);
}
/*