diff mbox series

dm-raid: fix address sanitizer warning in raid_status

Message ID alpine.LRH.2.02.2205151635090.15212@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive)
State New, archived
Headers show
Series dm-raid: fix address sanitizer warning in raid_status | expand

Commit Message

Mikulas Patocka May 15, 2022, 9:06 p.m. UTC
There is this warning when using a kernel with the address sanitizer and
running this testsuite:

BUG: KASAN: slab-out-of-bounds in raid_status+0x1747/0x2820 [dm_raid]
Read of size 4 at addr ffff888079d2c7e8 by task lvcreate/13319
CPU: 0 PID: 13319 Comm: lvcreate Not tainted 5.18.0-0.rc3.20220421gitb253435746d9a4a.30.eln117.x86_64 #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
 raid_status+0x1747/0x2820 [dm_raid]
 dm_ima_measure_on_table_load+0x4b8/0xca0 [dm_mod]
 table_load+0x35c/0x630 [dm_mod]
 ctl_ioctl+0x411/0x630 [dm_mod]
 dm_ctl_ioctl+0xa/0x10 [dm_mod]

The warning is caused by reading conf->max_nr_stripes in raid_status. The
code in raid_status reads mddev->private, casts it to struct r5conf and
reads the entry max_nr_stripes.

However, if we have different raid type than 4/5/6, mddev->private doesn't
point to struct r5conf; it may point to struct r0conf, struct r1conf,
struct r10conf or struct mpconf. If we cast a pointer to one of these
structs to struct r5conf, we will be reading invalid memory and KASAN
warns about it.

This patch fixes the bug by reading struct r5conf only if raid type is 4,
5 or 6.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org

 drivers/md/dm-raid.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

dm-devel mailing list
diff mbox series


Index: linux-2.6/drivers/md/dm-raid.c
--- linux-2.6.orig/drivers/md/dm-raid.c	2022-05-15 22:08:59.000000000 +0200
+++ linux-2.6/drivers/md/dm-raid.c	2022-05-15 22:08:59.000000000 +0200
@@ -3512,7 +3512,7 @@  static void raid_status(struct dm_target
 	struct raid_set *rs = ti->private;
 	struct mddev *mddev = &rs->md;
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf = rs_is_raid456(rs) ? mddev->private : NULL;
 	int i, max_nr_stripes = conf ? conf->max_nr_stripes : 0;
 	unsigned long recovery;
 	unsigned int raid_param_cnt = 1; /* at least 1 for chunksize */