On 1/22/20 1:01 PM, syzbot wrote: > syzbot has bisected this bug to: > > commit 58956317c8de52009d1a38a721474c24aef74fe7 > Author: David Ahern <dsahern@xxxxxxxxx> > Date: Fri Dec 7 20:24:57 2018 +0000 > > neighbor: Improve garbage collection > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=124a5985e00000 > start commit: d0f41851 net, ip_tunnel: fix namespaces move > git tree: net > final crash: https://syzkaller.appspot.com/x/report.txt?x=114a5985e00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=164a5985e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d9290aeb7e6cf1c4 > dashboard link: https://syzkaller.appspot.com/bug?extid=8ce4113dadc4789fac74 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11f99369e00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d85601e00000 > > Reported-by: syzbot+8ce4113dadc4789fac74@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 58956317c8de ("neighbor: Improve garbage collection") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > bisection looks bogus... It would be nice to have alternative helpers to conveniently replace some WARN_ON/WARN_ONCE/... and not having to hand-code stuff like : diff --git a/net/core/filter.c b/net/core/filter.c index 538f6a735a19f017df8e10149cb578107ddc8cbb..633988f7c81b3b4f015d827ccb485e8b227ad20b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6913,11 +6913,15 @@ static bool xdp_is_valid_access(int off, int size, void bpf_warn_invalid_xdp_action(u32 act) { + static bool __section(.data.once) warned; const u32 act_max = XDP_REDIRECT; - WARN_ONCE(1, "%s XDP return value %u, expect packet loss!\n", - act > act_max ? "Illegal" : "Driver unsupported", - act); + if (!warned) { + warned = true; + pr_err("%s XDP return value %u, expect packet loss!\n", + act > act_max ? "Illegal" : "Driver unsupported", act); + dump_stack(); + } } EXPORT_SYMBOL_GPL(bpf_warn_invalid_xdp_action);
