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dm ioctl: fix out of bounds array access when no devices 

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>
This commit is contained in:
Mikulas Patocka 2021-03-26 14:32:32 -04:00 committed by Mike Snitzer
parent 5424a0b867
commit 4edbe1d7bc
1 changed files with 1 additions and 1 deletions
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2
drivers/md/dm-ioctl.c
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@ -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;
}