Patch "radix-tree: fix oops after radix_tree_iter_retry" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

radix-tree: fix oops after radix_tree_iter_retry

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
radix-tree-fix-oops-after-radix_tree_iter_retry.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Konstantin Khlebnikov <[email protected]>
Date: Fri, 5 Feb 2016 15:37:01 -0800
Subject: radix-tree: fix oops after radix_tree_iter_retry

From: Konstantin Khlebnikov <[email protected]>

commit 732042821cfa106b3c20b9780e4c60fee9d68900 upstream.

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.

---
 include/linux/radix-tree.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -391,7 +391,7 @@ void **radix_tree_iter_retry(struct radi
  * @iter:	pointer to radix tree iterator
  * Returns:	current chunk size
  */
-static __always_inline unsigned
+static __always_inline long
 radix_tree_chunk_size(struct radix_tree_iter *iter)
 {
 	return iter->next_index - iter->index;

@@ -425,9 +425,9 @@ radix_tree_next_slot(void **slot, struct
 			return slot + offset + 1;
 		}
 	} else {
-		unsigned size = radix_tree_chunk_size(iter) - 1;
+		long size = radix_tree_chunk_size(iter);
 
-		while (size--) {
+		while (--size > 0) {
 			slot++;
 			iter->index++;
 			if (likely(*slot))

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/radix-tree-fix-oops-after-radix_tree_iter_retry.patch queue-4.4/mm-replace-vma_lock_anon_vma-with-anon_vma_lock_read-write.patch