[3.16.y-ckt stable] Patch "radix-tree: fix oops after radix_tree_iter_retry" has been added to the 3.16.y-ckt tree
Luis Henriques
luis.henriques at canonical.com
Thu Feb 25 18:34:09 UTC 2016
This is a note to let you know that I have just added a patch titled
radix-tree: fix oops after radix_tree_iter_retry
to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue
This patch is scheduled to be released in version 3.16.7-ckt25.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
---8<------------------------------------------------------------
>From 23c4228ea9c18dbaeba5d689e4e5138ab97b4ab5 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <koct9i at gmail.com>
Date: Fri, 5 Feb 2016 15:37:01 -0800
Subject: 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 at gmail.com>
Cc: Matthew Wilcox <willy at linux.intel.com>
Cc: Hugh Dickins <hughd at google.com>
Cc: Ohad Ben-Cohen <ohad at wizery.com>
Cc: Jeremiah Mahler <jmmahler at gmail.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
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 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))
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