From c750edf63ce45ff34155723b73828527c1d96353 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Fri, 5 Feb 2016 15:37:01 -0800 Subject: [PATCH] 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 Cc: Matthew Wilcox Cc: Hugh Dickins Cc: Ohad Ben-Cohen Cc: Jeremiah Mahler Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- include/linux/radix-tree.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 699fe2d933c9..e02e09f85fad 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -343,7 +343,7 @@ 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; @@ -377,9 +377,9 @@ 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))