Commit a63a5cf (dm: improve block integrity support) introduced a
two-phase initialization of a DM device's integrity profile. The
dm_table_set_integrity() call to blk_integrity_register() may deference
a NULL 'template_disk' due to an integrity profile mismatch.

An integrity profile mismatch can occur if the integrity profile for
devices in a DM table are changed between the call to
dm_table_prealloc_integrity() and dm_table_set_integrity() (possible
via table loads for stacked DM devices with integrity profiles).

Reported-by: Zdenek Kabelac <zkabelac@redhat.com> (coverity run)
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org # >= 2.6.39.y
---
drivers/md/dm-table.c | 13 +++++++------
1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 5e8e2f3..6cd8d95 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1260,14 +1260,15 @@ static void dm_table_set_integrity(struct dm_table *t)
return;

template_disk = dm_table_get_integrity_disk(t, true);
- if (!template_disk &&
- blk_integrity_is_initialized(dm_disk(t->md))) {
+ if (template_disk)
+ blk_integrity_register(dm_disk(t->md),
+ blk_get_integrity(template_disk));
+ else if (blk_integrity_is_initialized(dm_disk(t->md)))
DMWARN("%s: device no longer has a valid integrity profile",
dm_device_name(t->md));
- return;
- }
- blk_integrity_register(dm_disk(t->md),
- blk_get_integrity(template_disk));
+ else
+ DMWARN("%s: unable to establish an integrity profile",
+ dm_device_name(t->md));
}

void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
--
1.7.4.4

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