Btrfs:__add_inode_ref: out of bounds memory read when looking for extended ref.

Improper arithmetics when calculting the address of the extended ref could
lead to an out of bounds memory read and kernel panic.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
cc: stable@vger.kernel.org # v3.7+
Signed-off-by: Chris Mason <clm@fb.com>
(cherry picked from commit 36ebd77c9d5daaaa77594b536f515e7227851f71)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 952023ecf3f6df3a5688d8c4815f9c95ac6a52c3..80c0bd7a0e401b7b0146da9e5e7be511b1729659 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1010,7 +1010,7 @@ again:
                base = btrfs_item_ptr_offset(leaf, path->slots[0]);
 
                while (cur_offset < item_size) {
-                       extref = (struct btrfs_inode_extref *)base + cur_offset;
+                       extref = (struct btrfs_inode_extref *)(base + cur_offset);
 
                        victim_name_len = btrfs_inode_extref_name_len(leaf, extref);