xfs_scrub: fix missing scrub coverage for broken inodes

If INUMBERS says that an inode is allocated, but BULKSTAT skips over the
inode and BULKSTAT_SINGLE errors out when loading the inumber, there are
two possibilities: One, we're racing with ifree; or two, the inode is
corrupt and iget failed.

When this happens, the scrub_scan_all_inodes code will insert a dummy
bulkstat record with all fields zeroed except bs_ino and bs_blksize.
Hence the use of i_mode switches in phase3 to schedule file content
scrubbing are not entirely correct -- bs_mode==0 means "type unknown",
which ought to mean "schedule all scrubbers".

Unfortunately, the current code doesn't do that, so instead we schedule
no content scrubs.  If the broken file was actually a directory, we fail
to check the directory contents for further corruptions.

Found by using fuzzing with xfs/385 and core.format = 0.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

diff --git a/scrub/phase3.c b/scrub/phase3.c
index 9a26b92036c6c2e37886440dbecf05d8ecc315d1..b03b55250a3fe438cf85a6866a6a688cc2888898 100644 (file)
--- a/scrub/phase3.c
+++ b/scrub/phase3.c
@@ -166,16 +166,29 @@ scrub_inode(
        if (error)
                goto out;
 
-       if (S_ISLNK(bstat->bs_mode)) {
+       /*
+        * Check file data contents, e.g. symlink and directory entries.
+        *
+        * Note: bs_mode==0 occurs when inumbers says an inode is allocated,
+        * bulkstat skips the inode, and bulkstat_single errors out when
+        * loading the inode.  This could be due to racing with ifree, but it
+        * could be a corrupt inode.  Either way, schedule all the data fork
+        * content scrubbers.  Better to have them return -ENOENT than miss
+        * some coverage.
+        */
+       if (S_ISLNK(bstat->bs_mode) || !bstat->bs_mode) {
                /* Check symlink contents. */
                error = scrub_file(ctx, fd, bstat, XFS_SCRUB_TYPE_SYMLINK,
                                &alist);
-       } else if (S_ISDIR(bstat->bs_mode)) {
+               if (error)
+                       goto out;
+       }
+       if (S_ISDIR(bstat->bs_mode) || !bstat->bs_mode) {
                /* Check the directory entries. */
                error = scrub_file(ctx, fd, bstat, XFS_SCRUB_TYPE_DIR, &alist);
+               if (error)
+                       goto out;
        }
-       if (error)
-               goto out;
 
        /* Check all the extended attributes. */
        error = scrub_file(ctx, fd, bstat, XFS_SCRUB_TYPE_XATTR, &alist);