On 08.02.2022 21:00:26, Oliver Hartkopp wrote: > When receiving a CAN frame the current code logic does not consider > concurrently receiving processes which do not show up in real world > usage. > > Ziyang Xuan writes: > > The following syz problem is one of the scenarios. so->rx.len is > changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals > 0 before alloc_skb() and equals 4096 after alloc_skb(). That will > trigger skb_over_panic() in skb_put(). > > ======================================================= > CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0 > RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113 > Call Trace: > <TASK> > skb_over_panic net/core/skbuff.c:118 [inline] > skb_put.cold+0x24/0x24 net/core/skbuff.c:1990 > isotp_rcv_cf net/can/isotp.c:570 [inline] > isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668 > deliver net/can/af_can.c:574 [inline] > can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635 > can_receive+0x31d/0x580 net/can/af_can.c:665 > can_rcv+0x120/0x1c0 net/can/af_can.c:696 > __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465 > __netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579 > > Therefore we make sure the state changes and data structures stay > consistent at CAN frame reception time by adding a spin_lock in > isotp_rcv(). This fixes the issue reported by syzkaller but does not > affect real world operation. > > Link: https://lore.kernel.org/linux-can/d7e69278-d741-c706-65e1-e87623d9a8e8@xxxxxxxxxx/T/ > Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") > Reported-by: syzbot+4c63f36709a642f801c5@xxxxxxxxxxxxxxxxxxxxxxxxx > Reported-by: Ziyang Xuan <william.xuanziyang@xxxxxxxxxx> > Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx> Applied to linux-can/testing. Added stable on Cc. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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