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radix-tree: fix oops after radix_tree_iter_retry

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Helper radix_tree_iter_retry() resets next_index to the current index.
In following radix_tree_next_slot current chunk size becomes zero.  This
isn't checked and it tries to dereference null pointer in slot.

Tagged iterator is fine because retry happens only at slot 0 where tag
bitmask in iter->tags is filled with single bit.

Fixes: 46437f9a554f ("radix-tree: fix race in gang lookup")
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Jeremiah Mahler <jmmahler@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Konstantin Khlebnikov 2016-02-05 15:37:01 -08:00 committed by Linus Torvalds
parent b14fd334ff
commit 732042821c
1 changed files with 3 additions and 3 deletions
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6
include/linux/radix-tree.h
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@ -400,7 +400,7 @@ void **radix_tree_iter_retry(struct radix_tree_iter *iter)
* @iter: pointer to radix tree iterator * @iter: pointer to radix tree iterator
* Returns: current chunk size * Returns: current chunk size
*/ */
static __always_inline unsigned static __always_inline long
radix_tree_chunk_size(struct radix_tree_iter *iter) radix_tree_chunk_size(struct radix_tree_iter *iter)
{ {
return iter->next_index - iter->index; return iter->next_index - iter->index;
@ -434,9 +434,9 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
return slot + offset + 1; return slot + offset + 1;
} }
} else { } else {
unsigned size = radix_tree_chunk_size(iter) - 1; long size = radix_tree_chunk_size(iter);
while (size--) { while (--size > 0) {
slot++; slot++;
iter->index++; iter->index++;
if (likely(*slot)) if (likely(*slot))