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>
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 57eb0f6..467b69e 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -418,12 +418,14 @@
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 @@
flush_cache_user_range(vma, start, end);
}
+ up_read(&mm->mmap_sem);
}
/*