From: Mikulas Patocka mpatocka@redhat.com
commit 1fbeea217d8f297fe0e0956a1516d14ba97d0396 upstream.
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_...
================================================================== 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: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm-raid.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -3533,7 +3533,7 @@ 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 */