This is happening because flow_dissector_is_valid_access matches on ranges (bpf_ctx_range) whereas flow_dissector_convert_ctx_access matches on offsets (offsetof). Hence an access to offsetof(struct __sk_buff, data_end) + 1 is considered valid and then fails during convertion. I'll send a fix asap. Paul On Thu, Jul 31, 2025 at 06:43:05AM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit 0df1a55afa832f463f9ad68ddc5de92230f1bc8a > Author: Paul Chaignon <paul.chaignon@xxxxxxxxx> > Date: Tue Jul 1 18:36:15 2025 +0000 > > bpf: Warn on internal verifier errors > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17d6aca2580000 > start commit: e8d780dcd957 Merge tag 'slab-for-6.17' of git://git.kernel.. > git tree: upstream > final oops: https://syzkaller.appspot.com/x/report.txt?x=1436aca2580000 > console output: https://syzkaller.appspot.com/x/log.txt?x=1036aca2580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d32de89be62206c8 > dashboard link: https://syzkaller.appspot.com/bug?extid=ccac90e482b2a81d74aa > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=131049bc580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11cc2cf0580000 > > Reported-by: syzbot+ccac90e482b2a81d74aa@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 0df1a55afa83 ("bpf: Warn on internal verifier errors") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection
