From: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Subject: radix-tree: fix oops after radix_tree_iter_retry
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@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
Cc: Jeremiah Mahler <jmmahler@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/radix-tree.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN include/linux/radix-tree.h~radix-tree-fix-oops-after-radix_tree_iter_retry include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~radix-tree-fix-oops-after-radix_tree_iter_retry
+++ a/include/linux/radix-tree.h
@@ -400,7 +400,7 @@ 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;
@@ -434,9 +434,9 @@ 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))
_
--
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