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authorKonstantin Khlebnikov <koct9i@gmail.com>2016-02-06 02:37:01 +0300
committerLuis Henriques <luis.henriques@canonical.com>2016-02-25 13:34:45 +0300
commit23c4228ea9c18dbaeba5d689e4e5138ab97b4ab5 (patch)
treeb0305349b2deaaa937ddada487f2d58ed61c656d
parent745b4a707a3c9e522279973763562582f256a7b9 (diff)
downloadlinux-23c4228ea9c18dbaeba5d689e4e5138ab97b4ab5.tar.xz
radix-tree: fix oops after radix_tree_iter_retry
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. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
-rw-r--r--include/linux/radix-tree.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 1a2b2276ffb3..5d5174b59802 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -391,7 +391,7 @@ void **radix_tree_iter_retry(struct radix_tree_iter *iter)
* @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 radix_tree_iter *iter, unsigned flags)
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))