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authorRussell King <rmk+kernel@arm.linux.org.uk>2009-09-28 06:41:51 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-09-28 13:06:21 -0400
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 57eb0f6f6005..467b69ed1021 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)
418static inline void 418static inline void
419do_cache_op(unsigned long start, unsigned long end, int flags) 419do_cache_op(unsigned long start, unsigned long end, int flags)
420{ 420{
421 struct mm_struct *mm = current->active_mm;
421 struct vm_area_struct *vma; 422 struct vm_area_struct *vma;
422 423
423 if (end < start || flags) 424 if (end < start || flags)
424 return; 425 return;
425 426
426 vma = find_vma(current->active_mm, start); 427 down_read(&mm->mmap_sem);
428 vma = find_vma(mm, start);
427 if (vma && vma->vm_start < end) { 429 if (vma && vma->vm_start < end) {
428 if (start < vma->vm_start) 430 if (start < vma->vm_start)
429 start = vma->vm_start; 431 start = vma->vm_start;
@@ -432,6 +434,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
432 434
433 flush_cache_user_range(vma, start, end); 435 flush_cache_user_range(vma, start, end);
434 } 436 }
437 up_read(&mm->mmap_sem);
435} 438}
436 439
437/* 440/*