dvb-core: prevent some corruption the legacy ioctl

PATCH New Dan Carpenter 1 participant 1 message Jun 6, 2015

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Dan Carpenter

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2015-06-06 16:55 UTC #0 lore raw

PATCH 1/1 dvb-core: prevent some corruption the legacy ioctl

Quite a few of the ->diseqc_send_master_cmd() implementations don't check cmd->msg_len so it can lead to memory corruption.

Signed-off-by Dan Carpenter <[email protected]>

---
I don't think it ever makes sense for ->msg_len to be longer than ->msg but I am a newbie to this code.

drivers/media/dvb-core/dvb_frontend.c +7 -1

index a894d4c..aa6b48f 100644
@@ -2403,7 +2403,13 @@ static int dvb_frontend_ioctl_legacy(struct file *file,
 
 	case FE_DISEQC_SEND_MASTER_CMD:
 		if (fe->ops.diseqc_send_master_cmd) {
-			err = fe->ops.diseqc_send_master_cmd(fe, (struct dvb_diseqc_master_cmd*) parg);
+			struct dvb_diseqc_master_cmd *cmd = parg;
+
+			if (cmd->msg_len > sizeof(cmd->msg)) {
+				err = -EINVAL;
+				break;
+			}
+			err = fe->ops.diseqc_send_master_cmd(fe, cmd);
 			fepriv->state = FESTATE_DISEQC;
 			fepriv->status = 0;
 		}