On Mon, Apr 22, 2024 at 3:37 AM Björn Töpel <bjorn@xxxxxxxxxx> wrote: > > On Sat, 20 Apr 2024 at 00:42, Stanislav Fomichev <sdf@xxxxxxxxxx> wrote: > > > > On 04/19, Alexei Starovoitov wrote: > > > On Mon, Apr 8, 2024 at 8:53 PM syzbot > > > <syzbot+838346b979830606c854@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > Hello, > > > > > > > > syzbot found the following issue on: > > > > > > > > HEAD commit: fe46a7dd189e Merge tag 'sound-6.9-rc1' of git://git.kernel.. > > > > git tree: upstream > > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=12596223180000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=4d90a36f0cab495a > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=838346b979830606c854 > > > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=134ecbb5180000 > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=141a8b3d180000 > > > > > > > > Downloadable assets: > > > > disk image: https://storage.googleapis.com/syzbot-assets/f6c04726a2ae/disk-fe46a7dd.raw.xz > > > > vmlinux: https://storage.googleapis.com/syzbot-assets/09c26ce901ea/vmlinux-fe46a7dd.xz > > > > kernel image: https://storage.googleapis.com/syzbot-assets/134acf7f5322/bzImage-fe46a7dd.xz > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > Reported-by: syzbot+838346b979830606c854@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > > > > BUG: unable to handle page fault for address: 0000001000000112 > > > > #PF: supervisor read access in kernel mode > > > > #PF: error_code(0x0000) - not-present page > > > > PGD 800000002e7b1067 P4D 800000002e7b1067 PUD 0 > > > > Oops: 0000 [#1] PREEMPT SMP KASAN PTI > > > > CPU: 0 PID: 5060 Comm: syz-executor351 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 > > > > RIP: 0010:bpf_prog_a8e24a805b35c61b+0x19/0x1e > > > > Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc f3 0f 1e fa 0f 1f 44 00 00 66 90 55 48 89 e5 f3 0f 1e fa 31 c0 48 8b 7f 18 <8b> 7f 00 c9 c3 cc cc cc cc cc cc 40 03 00 00 cc cc cc cc cc cc cc > > > > RSP: 0018:ffffc90003b07b30 EFLAGS: 00010246 > > > > RAX: 0000000000000000 RBX: ffffc90000ace048 RCX: ffff88802aa89e00 > > > > RDX: 0000000000000000 RSI: ffffc90000ace048 RDI: 0000001000000112 > > > > RBP: ffffc90003b07b30 R08: ffffffff81bf633c R09: 1ffffffff2595ca0 > > > > R10: dffffc0000000000 R11: ffffffffa000095c R12: ffffc90000ace030 > > > > R13: ffff88802ac3ae28 R14: dffffc0000000000 R15: ffff88802ac3ae28 > > > > FS: 000055558f759380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000 > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > CR2: 0000001000000112 CR3: 0000000077cfa000 CR4: 00000000003506f0 > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > Call Trace: > > > > <TASK> > > > > bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] > > > > __bpf_prog_run include/linux/filter.h:657 [inline] > > > > bpf_prog_run include/linux/filter.h:664 [inline] > > > > bpf_prog_run_array_cg kernel/bpf/cgroup.c:51 [inline] > > > > __cgroup_bpf_run_filter_setsockopt+0x6fa/0x1040 kernel/bpf/cgroup.c:1830 > > > > do_sock_setsockopt+0x6b4/0x720 net/socket.c:2293 > > > > __sys_setsockopt+0x1ae/0x250 net/socket.c:2334 > > > > __do_sys_setsockopt net/socket.c:2343 [inline] > > > > __se_sys_setsockopt net/socket.c:2340 [inline] > > > > __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340 > > > > do_syscall_64+0xfb/0x240 > > > > entry_SYSCALL_64_after_hwframe+0x6d/0x75 > > > > > > This one looks interesting. > > > But I cannot reproduce it. > > > > > > Bjorn or Stan, > > > > > > Could you take a look? > > > > > > Probably a race in xdp dispatcher setup or the way cgroup-lsm > > > logic is doing it. > > > > Managed to repro it by hacking the C reproducer to attach bpf prog > > to /sys/fs/cgroup instead of syzkallers custom path. Will try to > > poke it a bit more.. > > Stan, did you get anywhere? Please share your hack, where you manage > to reproduce the issue. Yes, I think the problem is more naive. The syszbot reproducer manages to attach cgroup_skb program to a cgroup_sockopt hook :-/. I'll try to send a patch this week to fix it (need to write a proper selftest as well). > Cheers, > Björn
