linux-kernel - [PATCH] USB: rndis: Fix for handling garbled messages

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Message-Id: <1525957749-5391-1-git-send-email-phil.edworthy@renesas.com>
Date:   Thu, 10 May 2018 14:09:09 +0100
From:   Phil Edworthy <phil.edworthy@...esas.com>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michal Nazarewicz <mina86@...a86.com>,
        Michel Pollet <michel.pollet@...renesas.com>,
        Johannes Berg <johannes.berg@...el.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] USB: rndis: Fix for handling garbled messages

From: Michel Pollet <michel.pollet@...renesas.com>

A message can be forged to crash the stack; here we make sure we don't
completely break the system if this occurs

Signed-off-by: Michel Pollet <michel.pollet@...renesas.com>
---
 drivers/usb/gadget/function/rndis.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
index 51dd3e9..04c142c 100644
--- a/drivers/usb/gadget/function/rndis.c
+++ b/drivers/usb/gadget/function/rndis.c
@@ -851,6 +851,9 @@ int rndis_msg_parser(struct rndis_params *params, u8 *buf)
 		 */
 		pr_warn("%s: unknown RNDIS message 0x%08X len %d\n",
 			__func__, MsgType, MsgLength);
+		/* Garbled message can be huge, so limit what we display */
+		if (MsgLength > 16)
+			MsgLength = 16;
 		print_hex_dump_bytes(__func__, DUMP_PREFIX_OFFSET,
 				     buf, MsgLength);
 		break;
-- 
2.7.4