[syzbot] [bpf?] WARNING in bpf_mprog_pos_after

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ca5ab9638e92 Merge branch 'selftests-classid'
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=110ef2c2680000
kernel config: https://syzkaller.appspot.com/x/.config?x=e82a7781f9208c0d
dashboard link: https://syzkaller.appspot.com/bug?extid=2558ca3567a77b7af4e3
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3410dfa76b34/disk-ca5ab963.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/993bfbc60422/vmlinux-ca5ab963.xz
kernel image: https://storage.googleapis.com/syzbot-assets/40dff86d8c81/bzImage-ca5ab963.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2558ca...@syzkaller.appspotmail.com

8021q: adding VLAN 0 to HW filter on device batadv38
------------[ cut here ]------------
WARNING: CPU: 0 PID: 14695 at include/linux/bpf_mprog.h:198 bpf_mprog_total include/linux/bpf_mprog.h:198 [inline]
WARNING: CPU: 0 PID: 14695 at include/linux/bpf_mprog.h:198 bpf_mprog_pos_after+0x194/0x2b0 kernel/bpf/mprog.c:216
Modules linked in:
CPU: 0 PID: 14695 Comm: syz-executor.3 Not tainted 6.5.0-syzkaller-12718-gca5ab9638e92 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
RIP: 0010:bpf_mprog_total include/linux/bpf_mprog.h:198 [inline]
RIP: 0010:bpf_mprog_pos_after+0x194/0x2b0 kernel/bpf/mprog.c:216
Code: e8 03 42 80 3c 38 00 0f 85 f2 00 00 00 4d 3b 65 00 0f 85 26 ff ff ff e8 3a 55 e3 ff 8d 43 01 89 44 24 14 eb 48 e8 2c 55 e3 ff <0f> 0b e9 36 ff ff ff e8 20 55 e3 ff 4c 89 f2 48 b8 00 00 00 00 00
RSP: 0018:ffffc90004d87ac8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888043c88000 RSI: ffffffff81a47c94 RDI: 0000000000000005
RBP: 0000000000000040 R08: 0000000000000005 R09: 000000000000003f
R10: 0000000000000040 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888042c89418 R14: ffffc90004d87b98 R15: dffffc0000000000
FS: 00007f51b80af6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30823000 CR3: 0000000026678000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bpf_mprog_attach+0x433/0xfe0 kernel/bpf/mprog.c:266
tcx_prog_attach+0x2bd/0xbd0 kernel/bpf/tcx.c:39
bpf_prog_attach kernel/bpf/syscall.c:3848 [inline]
__sys_bpf+0x413e/0x4e90 kernel/bpf/syscall.c:5344
__do_sys_bpf kernel/bpf/syscall.c:5439 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5437 [inline]
__x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5437
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f51b727cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f51b80af0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f51b739bf80 RCX: 00007f51b727cae9
RDX: 0000000000000020 RSI: 0000000020000140 RDI: 0000000000000008
RBP: 00007f51b72c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f51b739bf80 R15: 00007ffe27bee9b8
</TASK>


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[Daniel Borkmann]

On 9/18/23 7:15 AM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: ca5ab9638e92 Merge branch 'selftests-classid'
> git tree: net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=110ef2c2680000
> kernel config: https://syzkaller.appspot.com/x/.config?x=e82a7781f9208c0d
> dashboard link: https://syzkaller.appspot.com/bug?extid=2558ca3567a77b7af4e3
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.

Will take a look, thx.