linux-kernel - Re: [syzbot] [bpf?] WARNING in dev_xdp

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Message-ID: <67ed6d26.050a0220.297a31.001d.GAE@google.com>
Date: Wed, 02 Apr 2025 10:00:22 -0700
From: syzbot <syzbot+08936936fe8132f91f1a@...kaller.appspotmail.com>
To: alexei.starovoitov@...il.com, andrii@...nel.org, ast@...nel.org, 
	bpf@...r.kernel.org, daniel@...earbox.net, davem@...emloft.net, 
	eddyz87@...il.com, edumazet@...gle.com, haoluo@...gle.com, hawk@...nel.org, 
	horms@...nel.org, john.fastabend@...il.com, jolsa@...nel.org, 
	kpsingh@...nel.org, kuba@...nel.org, linux-kernel@...r.kernel.org, 
	martin.lau@...ux.dev, netdev@...r.kernel.org, pabeni@...hat.com, 
	sdf@...ichev.me, song@...nel.org, stfomichev@...il.com, 
	syzkaller-bugs@...glegroups.com, yhs@...com, yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] WARNING in dev_xdp_install

syzbot has found a reproducer for the following issue on:

HEAD commit:    acc4d5ff0b61 Merge tag 'net-6.15-rc0' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124f9404580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=410c49aba9aeb859
dashboard link: https://syzkaller.appspot.com/bug?extid=08936936fe8132f91f1a
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109b7c3f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=103fa178580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-acc4d5ff.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aad60517b1c2/vmlinux-acc4d5ff.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27bf64833684/bzImage-acc4d5ff.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08936936fe8132f91f1a@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 3 PID: 5936 at ./include/net/netdev_lock.h:54 netdev_ops_assert_locked include/net/netdev_lock.h:54 [inline]
WARNING: CPU: 3 PID: 5936 at ./include/net/netdev_lock.h:54 dev_xdp_install+0x610/0x9b0 net/core/dev.c:9911
Modules linked in:
CPU: 3 UID: 0 PID: 5936 Comm: syz-executor652 Not tainted 6.14.0-syzkaller-12456-gacc4d5ff0b61 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:netdev_ops_assert_locked include/net/netdev_lock.h:54 [inline]
RIP: 0010:dev_xdp_install+0x610/0x9b0 net/core/dev.c:9911
Code: 8d bc 24 30 0d 00 00 be ff ff ff ff e8 b9 0d 28 02 31 ff 89 c5 89 c6 e8 4e f4 71 f8 85 ed 0f 85 59 fb ff ff e8 01 f9 71 f8 90 <0f> 0b 90 e9 4b fb ff ff e8 f3 f8 71 f8 49 8d bc 24 30 0d 00 00 be
RSP: 0018:ffffc900031d7950 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802ab20cc5 RCX: ffffffff89494752
RDX: ffff88802a4b2440 RSI: ffffffff8949475f RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88802ab20000
R13: ffffffff87119240 R14: ffffc90000a26000 R15: 0000000000000002
FS:  0000555586ae1380(0000) GS:ffff8880d6cbb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000140 CR3: 0000000030ae2000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dev_xdp_attach+0x6d1/0x16a0 net/core/dev.c:10094
 dev_xdp_attach_link net/core/dev.c:10113 [inline]
 bpf_xdp_link_attach+0x2c5/0x680 net/core/dev.c:10287
 link_create kernel/bpf/syscall.c:5418 [inline]
 __sys_bpf+0x19ef/0x4d80 kernel/bpf/syscall.c:5904
 __do_sys_bpf kernel/bpf/syscall.c:5941 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5939 [inline]
 __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5939
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x260 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa71b995919
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc061aef48 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa71b995919
RDX: 0000000000000040 RSI: 0000200000000200 RDI: 000000000000001c
RBP: 0000000000000000 R08: 0000555500000000 R09: 0000555500000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.