[dm-devel] Patch "dm raid: fix address sanitizer warning in raid_status" has been added to the 5.18-stable tree

[Sasha Levin]

This is a note to let you know that I've just added the patch titled

    dm raid: fix address sanitizer warning in raid_status

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dm-raid-fix-address-sanitizer-warning-in-raid_status.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.



commit 78121652de18db6e02f29395b05f1f73c1cf3fd2
Author: Mikulas Patocka <mpatocka at redhat.com>
Date:   Sun Jul 24 14:31:35 2022 -0400

    dm raid: fix address sanitizer warning in raid_status
    
    [ Upstream commit 1fbeea217d8f297fe0e0956a1516d14ba97d0396 ]
    
    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 at vger.kernel.org
    Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
    Signed-off-by: Mike Snitzer <snitzer at kernel.org>
    Signed-off-by: Sasha Levin <sashal at kernel.org>

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index e362a7471512..92e6b731f9d6 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3514,7 +3514,7 @@ 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 */