[26/38] dm table: avoid crash if integrity profile changes

Greg KH
2011-10-11T17:05:11Z

From: Mike Snitzer <snitzer@redhat.com>

commit 876fbba1db4a377f050a2bb49b474c7527b2995d upstream.

Commit a63a5cf (dm: improve block integrity support) introduced a
two-phase initialization of a DM device's integrity profile. This
patch avoids dereferencing a NULL 'template_disk' pointer in
blk_integrity_register() if there is an integrity profile mismatch in
dm_table_set_integrity().

This can occur if the integrity profiles for stacked devices in a DM
table are changed between the call to dm_table_prealloc_integrity() and
dm_table_set_integrity().

Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/dm-table.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1184,14 +1184,15 @@ static void dm_table_set_integrity(struc
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,