From 1fbeea217d8f297fe0e0956a1516d14ba97d0396 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Sun, 24 Jul 2022 14:31:35 -0400
Subject: [PATCH] dm raid: fix address sanitizer warning in raid_status
Git-commit: 1fbeea217d8f297fe0e0956a1516d14ba97d0396
Patch-mainline: v6.0-rc1
References: git-fixes
There is this warning when using a kernel with the address sanitizer
and running this testsuite:
https://gitlab.com/cki-project/kernel-tests/-/tree/main/storage/swraid/scsi_raid
==================================================================
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.<snip> #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
<TASK>
dump_stack_lvl+0x6a/0x9c
print_address_description.constprop.0+0x1f/0x1e0
print_report.cold+0x55/0x244
kasan_report+0xc9/0x100
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]
__x64_sys_ioctl+0x12a/0x1a0
do_syscall_64+0x5b/0x80
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.
Fix this bug by reading struct r5conf only if raid type is 4, 5 or 6.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/md/dm-raid.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index a438efc70e87..f41fd3cf5c7d 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3507,7 +3507,7 @@ static void raid_status(struct dm_target *ti, status_type_t type,
{
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 */
--
2.35.3