From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Oliver Hartkopp <socketcan@hartkopp.net>,
        syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com,
        Marc Kleine-Budde <mkl@pengutronix.de>
Subject: [PATCH 5.15 32/41] can: isotp: convert struct tpcon::{idx,len} to unsigned int
Date:   Fri, 14 Jan 2022 09:16:32 +0100
Message-Id: <20220114081546.236665396@linuxfoundation.org>
In-Reply-To: <20220114081545.158363487@linuxfoundation.org>
References: <20220114081545.158363487@linuxfoundation.org>
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From: Marc Kleine-Budde <mkl@pengutronix.de>

commit 5f33a09e769a9da0482f20a6770a342842443776 upstream.

In isotp_rcv_ff() 32 bit of data received over the network is assigned
to struct tpcon::len. Later in that function the length is checked for
the maximal supported length against MAX_MSG_LENGTH.

As struct tpcon::len is an "int" this check does not work, if the
provided length overflows the "int".

Later on struct tpcon::idx is compared against struct tpcon::len.

To fix this problem this patch converts both struct tpcon::{idx,len}
to unsigned int.

Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Link: https://lore.kernel.org/all/20220105132429.1170627-1-mkl@pengutronix.de
Cc: stable@vger.kernel.org
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Reported-by: syzbot+4c63f36709a642f801c5@syzkaller.appspotmail.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/can/isotp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/can/isotp.c
+++ b/net/can/isotp.c
@@ -119,8 +119,8 @@ enum {
 };
 
 struct tpcon {
-	int idx;
-	int len;
+	unsigned int idx;
+	unsigned int len;
 	u32 state;
 	u8 bs;
 	u8 sn;