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

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@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 76bbe6557eb60b1b4edb5da3a2ce6183a55d6d1c..0a8194955e6b908fbc52e5adda0edb3c11544f7a 100644 (file)
--- 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);