Re: [syzbot] general protection fault in inet_csk_accept

On Fri, 2021-12-10 at 03:13 -0800, Eric Dumazet wrote:

On Fri, Dec 10, 2021 at 3:09 AM syzbot
[off-list ref] wrote:

quoted

Hello,

syzbot found the following issue on:

HEAD commit:    2a987e65025e Merge tag 'perf-tools-fixes-for-v5.16-2021-12..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=166f73adb00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=221ffc09e39ebbd1
dashboard link: https://syzkaller.appspot.com/bug?extid=e4d843bb96a9431e6331
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=16280ae5b00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1000fdc5b00000

The issue was bisected to:

Note to MPTCP maintainers, I think this issue is MPTCP one, 

Indeed it is, thanks for the head-up!

and the bisection result shown here seems not relevant.

yep.

The C repro is however correct, I trigger an immediate crash.

The repro is not triggering here - but I'm using a different kconfig.
Still the repro itself gives a good hint on the root cause. I'm testing
a patch with syzbot.

Thanks!

Paolo