[PATCH 3.16.y-ckt 086/165] Btrfs:__add_inode_ref: out of bounds memory read when looking for extended ref.

[Luis Henriques]

3.16.7-ckt9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Quentin Casasnovas <quentin.casasnovas at oracle.com>

commit dd9ef135e3542ffc621c4eb7f0091870ec7a1504 upstream.

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 at oracle.com>
Reviewed-by: David Sterba <dsterba at suse.cz>
Signed-off-by: Chris Mason <clm at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/btrfs/tree-log.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 76bbe6557eb6..0a8194955e6b 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1007,7 +1007,7 @@ 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);