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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From 732042821cfa106b3c20b9780e4c60fee9d68900 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <koct9i@gmail.com>
Date: Fri, 5 Feb 2016 15:37:01 -0800
Subject: radix-tree: fix oops after radix_tree_iter_retry

From: Konstantin Khlebnikov <koct9i@gmail.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -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 koct9i@gmail.com 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