[syzbot] [net?] WARNING in netif_rx_mode_run

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c8993263ffd3 bpf: Add Jiayuan Chen to sockmap maintainers
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=156e9bce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4caf64b1ee83dac0
dashboard link: https://syzkaller.appspot.com/bug?extid=f2421634072a4b47071e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=121aee36580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136e9bce580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bd0898114f61/disk-c8993263.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b3988a1716d/vmlinux-c8993263.xz
kernel image: https://storage.googleapis.com/syzbot-assets/eedc9b64bb9f/bzImage-c8993263.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f24216...@syzkaller.appspotmail.com

RSP: 002b:00007ffde2b3c518 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fece9c15fa0 RCX: 00007fece999ce59
RDX: 0000200000000000 RSI: 0000000000008931 RDI: 0000000000000003
RBP: 00007ffde2b3c580 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fece9c15fac R14: 00007fece9c15fa0 R15: 00007fece9c15fa0
</TASK>
------------[ cut here ]------------
netdevice: dummy0: failed to sync uc/mc addresses
WARNING: net/core/dev_addr_lists.c:1278 at netif_rx_mode_run+0xd55/0x1290 net/core/dev_addr_lists.c:1278, CPU#1: syz.0.17/5854
Modules linked in:
CPU: 1 UID: 0 PID: 5854 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:netif_rx_mode_run+0xe82/0x1290 net/core/dev_addr_lists.c:1278
Code: 3a 48 c7 c2 a0 ec dd 8c eb 1a e8 e9 8a 43 f8 48 c7 c2 20 eb dd 8c eb 0c e8 db 8a 43 f8 48 c7 c2 20 ec dd 8c 4c 89 f7 4c 89 fe <67> 48 0f b9 3a 48 8b 5c 24 38 48 8b 7c 24 48 e8 da be 29 02 42 c7
RSP: 0018:ffffc90002e2f9e0 EFLAGS: 00010293
RAX: ffffffff898241b7 RBX: 0000000000000001 RCX: ffff88802dcd5c40
RDX: ffffffff8cddeb20 RSI: ffff888025bb6120 RDI: ffffffff903fb9d0
RBP: ffffc90002e2fbb8 R08: ffff88802dcd5c40 R09: 0000000000000006
R10: 0000000000000005 R11: 0000000000000000 R12: ffff888025bb6120
R13: dffffc0000000000 R14: ffffffff903fb9d0 R15: ffff888025bb6120
FS: 000055556040b500(0000) GS:ffff888125388000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 0000000033696000 CR4: 00000000003526f0
Call Trace:
<TASK>
netif_rx_mode_sync+0x171/0x1e0 net/core/dev_addr_lists.c:1428
dev_ifsioc+0xf51/0x1330 net/core/dev_ioctl.c:596
dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:816
sock_do_ioctl+0x23e/0x320 net/socket.c:1327
sock_ioctl+0x5c6/0x7f0 net/socket.c:1434
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fece999ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffde2b3c518 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fece9c15fa0 RCX: 00007fece999ce59
RDX: 0000200000000000 RSI: 0000000000008931 RDI: 0000000000000003
RBP: 00007ffde2b3c580 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fece9c15fac R14: 00007fece9c15fa0 R15: 00007fece9c15fa0
</TASK>
----------------
Code disassembly (best guess):
0: 3a 48 c7 cmp -0x39(%rax),%cl
3: c2 a0 ec ret $0xeca0
6: dd 8c eb 1a e8 e9 8a fisttpll -0x751617e6(%rbx,%rbp,8)
d: 43 f8 rex.XB clc
f: 48 c7 c2 20 eb dd 8c mov $0xffffffff8cddeb20,%rdx
16: eb 0c jmp 0x24
18: e8 db 8a 43 f8 call 0xf8438af8
1d: 48 c7 c2 20 ec dd 8c mov $0xffffffff8cddec20,%rdx
24: 4c 89 f7 mov %r14,%rdi
27: 4c 89 fe mov %r15,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 8b 5c 24 38 mov 0x38(%rsp),%rbx
34: 48 8b 7c 24 48 mov 0x48(%rsp),%rdi
39: e8 da be 29 02 call 0x229bf18
3e: 42 rex.X
3f: c7 .byte 0xc7


---
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***

Subject: test
Author: yun....@windriver.com

#syz test

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
lost connection to test machine



Tested on:

commit: 523d2f42 selftests/bpf: Fix test for refinement of sin..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10f26596580000

kernel config: https://syzkaller.appspot.com/x/.config?x=4caf64b1ee83dac0
dashboard link: https://syzkaller.appspot.com/bug?extid=f2421634072a4b47071e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=14f6782e580000