[media] firewire: firedtv-avc: potential buffer overflow

"program_info_length" is user controlled and can go up to 4095.  The
operand[] array has 509 bytes so we need to add a limit here to prevent
buffer overflows.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/firewire/firedtv-avc.c b/drivers/media/firewire/firedtv-avc.c
index d1a1a13..ac17567 100644 (file)
--- a/drivers/media/firewire/firedtv-avc.c
+++ b/drivers/media/firewire/firedtv-avc.c
@@ -1157,6 +1157,10 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length)
                if (pmt_cmd_id != 1 && pmt_cmd_id != 4)
                        dev_err(fdtv->device,
                                "invalid pmt_cmd_id %d\n", pmt_cmd_id);
+               if (program_info_length > sizeof(c->operand) - write_pos) {
+                       ret = -EINVAL;
+                       goto out;
+               }
 
                memcpy(&c->operand[write_pos], &msg[read_pos],
                       program_info_length);
@@ -1180,6 +1184,11 @@ int avc_ca_pmt(struct firedtv *fdtv, char *msg, int length)
                                dev_err(fdtv->device, "invalid pmt_cmd_id %d "
                                        "at stream level\n", pmt_cmd_id);
 
+                       if (es_info_length > sizeof(c->operand) - write_pos) {
+                               ret = -EINVAL;
+                               goto out;
+                       }
+
                        memcpy(&c->operand[write_pos], &msg[read_pos],
                               es_info_length);
                        read_pos += es_info_length;