Re: [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default

On Tue, 27 Jul 2021 05:47:21 -0700
syzbot [off-list ref] wrote:

Hello,

syzbot found the following issue on:

HEAD commit:    90d856e71443 Add linux-next specific files for
20210723 git tree:       linux-next
console output:
https://syzkaller.appspot.com/x/log.txt?x=133fd00a300000 kernel
config:  https://syzkaller.appspot.com/x/.config?x=298516715f6ad5cd
dashboard link:
https://syzkaller.appspot.com/bug?extid=9cd5837a045bbee5b810
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU
Binutils for Debian) 2.35.1 syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=1263bba6300000 C
reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1066b4d4300000

IMPORTANT: if you fix the issue, please add the following tag to the
commit: Reported-by:
syzbot+9cd5837a045bbee5b810@syzkaller.appspotmail.com

netlink: 228 bytes leftover after parsing attributes in process
`syz-executor669'.
================================================================================

The first thing that comes in mind is to check up->dirmask value


#syz test
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master 


With regards,
Pavel Skripkin