From 4edbe1d7bcffcd6269f3b5eb63f710393ff2ec7a Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Fri, 26 Mar 2021 14:32:32 -0400
Subject: [PATCH] dm ioctl: fix out of bounds array access when no devices
Git-commit: 4edbe1d7bcffcd6269f3b5eb63f710393ff2ec7a
Patch-mainline: v5.12-rc5
References: CVE-2021-31916 bsc#1192781
If there are not any dm devices, we need to zero the "dev" argument in
the first structure dm_name_list. However, this can cause out of
bounds write, because the "needed" variable is zero and len may be
less than eight.
Fix this bug by reporting DM_BUFFER_FULL_FLAG if the result buffer is
too small to hold the "nl->dev" value.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/md/dm-ioctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 5e306bba4375..1ca65b434f1f 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -529,7 +529,7 @@ static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_
* Grab our output buffer.
*/
nl = orig_nl = get_result_buffer(param, param_size, &len);
- if (len < needed) {
+ if (len < needed || len < sizeof(nl->dev)) {
param->flags |= DM_BUFFER_FULL_FLAG;
goto out;
}
--
2.26.2