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 dd9ef135e3542ffc621c4eb7f0091870ec7a1504)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a91e2113f21786122d1735cbb708c7a9280ebf55..06dd8e9d45d6944485d9c58390e2f2303ffa48ea 100644 (file)
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1012,7 +1012,7 @@ 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);