From: Mikulas Patocka mpatocka@redhat.com
stable inclusion from linux-4.19.192 commit 1ff004c41c8205d7677f7b9d7da238a5d9a29274
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commit c699a0db2d62e3bbb7f0bf35c87edbc8d23e3062 upstream.
The following commands will crash the kernel:
modprobe brd rd_size=1048576 dmsetup create o --table "0 `blockdev --getsize /dev/ram0` snapshot-origin /dev/ram0" dmsetup create s --table "0 `blockdev --getsize /dev/ram0` snapshot /dev/ram0 /dev/ram1 N 0"
The reason is that when we test for zero chunk size, we jump to the label bad_read_metadata without setting the "r" variable. The function snapshot_ctr destroys all the structures and then exits with "r == 0". The kernel then crashes because it falsely believes that snapshot_ctr succeeded.
In order to fix the bug, we set the variable "r" to -EINVAL.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/dm-snap.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 9e930a150aa29..7d96836294713 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1286,6 +1286,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
if (!s->store->chunk_size) { ti->error = "Chunk size not set"; + r = -EINVAL; goto bad_read_metadata; }