dm ioctl: prevent empty message

Detect invalid empty messages in core dm instead of requiring every target to
check this.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4cacdad2270a345e1ef8455eddf5c2a2838a22e1..1622a6bc0bfd08752252df0e3c6ccb4c76cab70d 100644 (file)
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1402,6 +1402,11 @@ static int target_message(struct dm_ioctl *param, size_t param_size)
                goto out;
        }
 
+       if (!argc) {
+               DMWARN("Empty message received.");
+               goto out;
+       }
+
        table = dm_get_live_table(md);
        if (!table)
                goto out_argv;