[syzbot] [bpf?] BUG: unable to handle kernel paging request in bpf_prog_ADDR (2)

[syzbot]

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+838346...@syzkaller.appspotmail.com

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
RIP: 0033:0x7fb234535cc9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd33db0138 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fb234535cc9
RDX: 0000000000000010 RSI: 0000000000000112 RDI: 0000000000000007
RBP: 0000000000000006 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000055558f759338
R13: 0000000000000010 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
CR2: 0000001000000112
---[ end trace 0000000000000000 ]---
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
----------------
Code disassembly (best guess):
0: cc int3
1: cc int3
2: cc int3
3: cc int3
4: cc int3
5: cc int3
6: cc int3
7: cc int3
8: cc int3
9: cc int3
a: cc int3
b: cc int3
c: cc int3
d: cc int3
e: cc int3
f: cc int3
10: cc int3
11: f3 0f 1e fa endbr64
15: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
1a: 66 90 xchg %ax,%ax
1c: 55 push %rbp
1d: 48 89 e5 mov %rsp,%rbp
20: f3 0f 1e fa endbr64
24: 31 c0 xor %eax,%eax
26: 48 8b 7f 18 mov 0x18(%rdi),%rdi
* 2a: 8b 7f 00 mov 0x0(%rdi),%edi <-- trapping instruction
2d: c9 leave
2e: c3 ret
2f: cc int3
30: cc int3
31: cc int3
32: cc int3
33: cc int3
34: cc int3
35: 40 03 00 rex add (%rax),%eax
38: 00 cc add %cl,%ah
3a: cc int3
3b: cc int3
3c: cc int3
3d: cc int3
3e: cc int3
3f: cc int3


---
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[Alexei Starovoitov]

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.

[Stanislav Fomichev]

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..

[Björn Töpel]

Stan, did you get anywhere? Please share your hack, where you manage
to reproduce the issue.


Cheers,
Björn

[Stanislav Fomichev]

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