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 --- net/can/isotp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/can/isotp.c b/net/can/isotp.c index df6968b28bf4..02cbcb2ecf0d 100644 --- 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;