[dm-devel] [PATCH] dm-integrity: test for corrupted disk format

[Mikulas Patocka]

If the dm-integrity superblock was corrupted in such a way that the
journal_sections field was zero, the integrity target would deadlock,
because it would wait forever for free space in the journal.

This patch detects this situation and refuses to activate the device in
this case.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Cc: stable at vger.kernel.org
Fixes: 7eada909bfd7 ("dm: add integrity target")

---
 drivers/md/dm-integrity.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c
+++ linux-2.6/drivers/md/dm-integrity.c
@@ -3020,6 +3020,11 @@ static int dm_integrity_ctr(struct dm_ta
 		ti->error = "Block size doesn't match the information in superblock";
 		goto bad;
 	}
+	if (!le32_to_cpu(ic->sb->journal_sections)) {
+		r = -EINVAL;
+		ti->error = "Corrupted superblock, journal_sections is 0";
+		goto bad;
+	}
 	/* make sure that ti->max_io_len doesn't overflow */
 	if (ic->sb->log2_interleave_sectors < MIN_LOG2_INTERLEAVE_SECTORS ||
 	    ic->sb->log2_interleave_sectors > MAX_LOG2_INTERLEAVE_SECTORS) {