linux-kernel - [PATCH 5.12 077/173] btrfs: promote debugging asserts to full-fledged checks in validate

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Date:   Mon, 14 Jun 2021 12:26:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+a6bf271c02e4fe66b4e4@...kaller.appspotmail.com,
        Johannes Thumshirn <johannes.thumshirn@....com>,
        Qu Wenruo <wqu@...e.com>, Nikolay Borisov <nborisov@...e.com>,
        David Sterba <dsterba@...e.com>
Subject: [PATCH 5.12 077/173] btrfs: promote debugging asserts to full-fledged checks in validate_super

From: Nikolay Borisov <nborisov@...e.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@...kaller.appspotmail.com
CC: stable@...r.kernel.org # 5.4+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@....com>
Reviewed-by: Qu Wenruo <wqu@...e.com>
Signed-off-by: Nikolay Borisov <nborisov@...e.com>
Reviewed-by: David Sterba <dsterba@...e.com>
[ add uuids to the messages ]
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -2558,6 +2558,24 @@ 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,
@@ -3185,14 +3203,6 @@ int __cold open_ctree(struct super_block
 
 	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) {