Re: [syzbot] BUG: missing reserved tailroom

[Toke Høiland-Jørgensen]

Martin KaFai Lau <kafai@xxxxxx> writes:

> On Thu, Mar 10, 2022 at 10:37:20AM -0800, syzbot wrote:
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    de55c9a1967c Merge branch 'Add support for transmitting pa..
>> git tree:       bpf-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14ce88ad700000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=2fa13781bcea50fc
>> dashboard link: https://syzkaller.appspot.com/bug?extid=0e91362d99386dc5de99
>> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11f36345700000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14c8ca65700000
>> 
>> The issue was bisected to:
>> 
>> commit b530e9e1063ed2b817eae7eec6ed2daa8be11608
>> Author: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
>> Date:   Wed Mar 9 10:53:42 2022 +0000
>> 
>>     bpf: Add "live packet" mode for XDP in BPF_PROG_RUN
>> 
>> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17696e55700000
>> final oops:     https://syzkaller.appspot.com/x/report.txt?x=14e96e55700000
>> console output: https://syzkaller.appspot.com/x/log.txt?x=10e96e55700000
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+0e91362d99386dc5de99@xxxxxxxxxxxxxxxxxxxxxxxxx
>> Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN")
>> 
>> ------------[ cut here ]------------
>> XDP_WARN: xdp_update_frame_from_buff(line:274): Driver BUG: missing reserved tailroom
>> WARNING: CPU: 0 PID: 3590 at net/core/xdp.c:599 xdp_warn+0x28/0x30 net/core/xdp.c:599
> Toke, please take a look.

Right, I see the problem; will send a fix!

-Toke