[PATCH 5.4 44/84] btrfs: promote debugging asserts to full-fledged checks in validate_super

Greg Kroah-Hartman
2021-06-14T10:58:46Z

From: Nikolay Borisov <nborisov@suse.com>

commit aefd7f7065567a4666f42c0fc8cdb379d2e036bf upstream.

Syzbot managed to trigger this assert while performing its fuzzing.
Turns out it's better to have those asserts turned into full-fledged
checks so that in case buggy btrfs images are mounted the users gets
an error and mounting is stopped. Alternatively with CONFIG_BTRFS_ASSERT
disabled such image would have been erroneously allowed to be mounted.

Reported-by: syzbot+a6bf271c02e4fe66b4e4@syzkaller.appspotmail.com
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add uuids to the messages ]
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/disk-io.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)

--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2463,6 +2463,24 @@ static int validate_super(struct btrfs_f
ret = -EINVAL;
}

+ if (memcmp(fs_info->fs_devices->fsid, fs_info->super_copy->fsid,
+ BTRFS_FSID_SIZE)) {
+ btrfs_err(fs_info,
+ "superblock fsid doesn't match fsid of fs_devices: %pU != %pU",
+ fs_info->super_copy->fsid, fs_info->fs_devices->fsid);
+ ret = -EINVAL;
+ }
+
+ if (btrfs_fs_incompat(fs_info, METADATA_UUID) &&
+ memcmp(fs_info->fs_devices->metadata_uuid,
+ fs_info->super_copy->metadata_uuid, BTRFS_FSID_SIZE)) {
+ btrfs_err(fs_info,
+"superblock metadata_uuid doesn't match metadata uuid of fs_devices: %pU != %pU",
+ fs_info->super_copy->metadata_uuid,
+ fs_info->fs_devices->metadata_uuid);
+ ret = -EINVAL;
+ }
+
if (memcmp(fs_info->fs_devices->metadata_uuid, sb->dev_item.fsid,
BTRFS_FSID_SIZE) != 0) {
btrfs_err(fs_info,
@@ -2837,14 +2855,6 @@ int open_ctree(struct super_block *sb,

disk_super = fs_info->super_copy;

- ASSERT(!memcmp(fs_info->fs_devices->fsid, fs_info->super_copy->fsid,
- BTRFS_FSID_SIZE));
-
- if (btrfs_fs_incompat(fs_info, METADATA_UUID)) {
- ASSERT(!memcmp(fs_info->fs_devices->metadata_uuid,
- fs_info->super_copy->metadata_uuid,
- BTRFS_FSID_SIZE));
- }

features = btrfs_super_flags(disk_super);
if (features & BTRFS_SUPER_FLAG_CHANGING_FSID_V2) {