[PATCH 4.12 19/31] dm integrity: test for corrupted disk format during table load

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit bc86a41e96c5b6f07453c405e036d95acc673389 upstream.

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.

Detect this situation and refuse to activate the device.

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Fixes: 7eada909bfd7 ("dm: add integrity target")
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -3021,6 +3021,11 @@ 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) {