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* [PATCH] [media] dvb-core: prevent some corruption the legacy ioctl
@ 2015-06-06 16:55 Dan Carpenter
  0 siblings, 0 replies; only message in thread
From: Dan Carpenter @ 2015-06-06 16:55 UTC (permalink / raw)
  To: Mauro Carvalho Chehab
  Cc: Shuah Khan, Akihiro Tsukada, Antti Palosaari, linux-media,
	kernel-janitors

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

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index a894d4c..aa6b48f 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -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;
 		}

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2015-06-06 16:55 [PATCH] [media] dvb-core: prevent some corruption the legacy ioctl Dan Carpenter

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