From: Mike Snitzer 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 Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon Cc: stable@kernel.org # 2.6.39 --- drivers/md/dm-table.c | 13 +++++++------ drivers/md/dm-table.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) Index: linux-3.1-rc7/drivers/md/dm-table.c =================================================================== --- linux-3.1-rc7.orig/drivers/md/dm-table.c +++ linux-3.1-rc7/drivers/md/dm-table.c @@ -1238,14 +1238,15 @@ 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)); } static int device_flush_capable(struct dm_target *ti, struct dm_dev *dev,