On 01/17/2018 09:07 AM, Oliver Hartkopp wrote: > > > On 01/17/2018 08:12 AM, Eric Biggers wrote: >> On Wed, Jan 17, 2018 at 07:39:24AM +0100, Oliver Hartkopp wrote: >>> >>> >>> On 01/16/2018 07:11 PM, Dmitry Vyukov wrote: >>>> On Tue, Jan 16, 2018 at 7:07 PM, Marc Kleine-Budde <m...@pengutronix.de> >>>> wrote: >>>>> On 01/16/2018 06:58 PM, syzbot wrote: >>>>>> Hello, >>>>>> >>>>>> syzkaller hit the following crash on >>>>>> a8750ddca918032d6349adbf9a4b6555e7db20da >>>>>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master >>>>>> compiler: gcc (GCC) 7.1.1 20170620 >>>>>> .config is attached >>>>>> Raw console output is attached. >>>>>> C reproducer is attached >>>>>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ >>>>>> for information about syzkaller reproducers >>>>>> >>>>>> >>>>>> IMPORTANT: if you fix the bug, please add the following tag to the >>>>>> commit: >>>>>> Reported-by: syzbot+4386709c0c1284dca...@syzkaller.appspotmail.com >>>>>> It will help syzbot understand when the bug is fixed. See footer for >>>>>> details. >>>>>> If you forward the report, please keep this part and the footer. >>>>>> >>>>>> device eql entered promiscuous mode >>>>>> ------------[ cut here ]------------ >>>>>> PF_CAN: dropped non conform CAN skbuf: dev type 65534, len 42, datalen 0 >>>>>> WARNING: CPU: 0 PID: 3650 at net/can/af_can.c:729 can_rcv+0x1c5/0x200 >>>>>> net/can/af_can.c:724 >>>>>> Kernel panic - not syncing: panic_on_warn set ... >>>>> >>>>> Invalid packages generate a warning (WARN_ONCE()), and you have >>>>> panic_on_warn active. Should we better silently drop these CAN packages? >>>> >>>> Hi, >>>> >>>> pr_warn_once() will be more appropriate. It prints a single line. >>>> >>> >>> The idea behind this WARN() is to detect really bad things that might have >>> happen on network driver level: >>> >>> The CAN subsystem registers with dev_add_pack() for ETH_P_CAN and >>> ETH_P_CANFD only. These ETH_P_ types are only allowed to be created by CAN >>> network devices (like vcan, vxcan, and real CAN drivers). >>> >>> I don't have any strong opinion on using WARN() or pr_warn_once(). >>> Is this detected violation worth using WARN(), as something already must >>> have gone really wrong to trigger this issue? >>> >> >> WARN() indicates a kernel bug. If it's instead "userspace did something >> stupid", or "someone sent some unexpected network packet", it needs to be >> pr_warn_once(), pr_warn_ratelimited(), or removed entirely. > > Ok. Thanks for the explanation! > It is "some bogus network driver sent something unexpected" - but that > does not harm the entire system. > > pr_warn_once() seems the right way to go then.
Is this an Acked-by for both patches? Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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