btrfs: ref-verify: free ref cache before clearing mount opt

commit f03e274a8b29d1d1c1bbd7f764766cb5ca537ab7 upstream.

As clearing REF_VERIFY mount option indicates there were some errors in a
ref-verify process, a ref cache is not relevant anymore and should be
freed.

btrfs_free_ref_cache() requires REF_VERIFY option being set so call
it just before clearing the mount option.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Reported-by: syzbot+be14ed7728594dc8bd42@syzkaller.appspotmail.com
Fixes: fd708b81d972 ("Btrfs: add a extent ref verify tool")
CC: stable@vger.kernel.org # 5.4+
Closes: https://lore.kernel.org/lkml/000000000000e5a65c05ee832054@google.com/
Reported-by: syzbot+c563a3c79927971f950f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/0000000000007fe09705fdc6086c@google.com/
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/ref-verify.c b/fs/btrfs/ref-verify.c
index e646662..1ea5bfb 100644 (file)
--- a/fs/btrfs/ref-verify.c
+++ b/fs/btrfs/ref-verify.c
@@ -886,8 +886,10 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 out_unlock:
        spin_unlock(&fs_info->ref_verify_lock);
 out:
-       if (ret)
+       if (ret) {
+               btrfs_free_ref_cache(fs_info);
                btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
+       }
        return ret;
 }
 
@@ -1018,8 +1020,8 @@ int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
                }
        }
        if (ret) {
-               btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
                btrfs_free_ref_cache(fs_info);
+               btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
        }
        btrfs_free_path(path);
        return ret;