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: Sasha Levin <sasha.levin@oracle.com>

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index ee1c60454a5f1ab74645128710114fc6e8580534..8b40b35e5e0e39a7533e862a9ef26fd9a4a1a9e0 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);