From c7dd13805f8b8fc1ce3b6d40f6aff47e66b72ad2 Mon Sep 17 00:00:00 2001

From: Szymon Heidrich <szymon.heidrich@gmail.com>

Date: Tue, 3 Jan 2023 10:17:09 +0100

Subject: [PATCH] usb: rndis_host: Secure rndis_query check against int

 overflow

Git-commit: c7dd13805f8b8fc1ce3b6d40f6aff47e66b72ad2

References: CVE-2023-23559 bsc#1207051

Patch-mainline: v6.2-rc3

Variables off and len typed as uint32 in rndis_query function

are controlled by incoming RNDIS response message thus their

value may be manipulated. Setting off to a unexpectetly large

value will cause the sum with len and 8 to overflow and pass

the implemented validation step. Consequently the response

pointer will be referring to a location past the expected

buffer boundaries allowing information leakage e.g. via

RNDIS_OID_802_3_PERMANENT_ADDRESS OID.

Fixes: ddda08624013 ("USB: rndis_host, various cleanups")

Signed-off-by: Szymon Heidrich <szymon.heidrich@gmail.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Oliver Neukum <oneukum@suse.com>

---

 drivers/net/usb/rndis_host.c | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c

index f79333fe1783..7b3739b29c8f 100644

--- a/drivers/net/usb/rndis_host.c

+++ b/drivers/net/usb/rndis_host.c

@@ -255,7 +255,8 @@ static int rndis_query(struct usbnet *dev, struct usb_interface *intf,

 	off = le32_to_cpu(u.get_c->offset);

 	len = le32_to_cpu(u.get_c->len);

-	if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))

+	if (unlikely((off > CONTROL_BUFFER_SIZE - 8) ||

+		     (len > CONTROL_BUFFER_SIZE - 8 - off)))

 		goto response_error;

 	if (*reply_len != -1 && len != *reply_len)

-- 

2.39.1