linux-kernel - Re: [syzbot] [net?] WARNING in ipv6_add

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Message-ID: <Z_VJP8bbKRyOAeyQ@mini-arch>
Date: Tue, 8 Apr 2025 09:05:19 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: syzbot <syzbot+3ab016dc5f28b32452c1@...kaller.appspotmail.com>
Cc: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com,
	horms@...nel.org, kuba@...nel.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, pabeni@...hat.com,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] WARNING in ipv6_add_dev

On 04/08, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0af2f6be1b42 Linux 6.15-rc1
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=166dffb0580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=66996a2350ef05e0
> dashboard link: https://syzkaller.appspot.com/bug?extid=3ab016dc5f28b32452c1
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/2bd38b4e51ec/disk-0af2f6be.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/928b4d433463/vmlinux-0af2f6be.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9c0fa5febc31/bzImage-0af2f6be.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3ab016dc5f28b32452c1@...kaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 813 at ./include/net/netdev_lock.h:54 netdev_ops_assert_locked include/net/netdev_lock.h:54 [inline]
> WARNING: CPU: 1 PID: 813 at ./include/net/netdev_lock.h:54 ipv6_add_dev+0x104c/0x1430 net/ipv6/addrconf.c:381
> Modules linked in:
> CPU: 1 UID: 0 PID: 813 Comm: kworker/u8:1 Not tainted 6.15.0-rc1-syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
> Workqueue: events_unbound linkwatch_event
> RIP: 0010:netdev_ops_assert_locked include/net/netdev_lock.h:54 [inline]
> RIP: 0010:ipv6_add_dev+0x104c/0x1430 net/ipv6/addrconf.c:381
> Code: ff ff e8 67 5d fe f6 48 bd 00 00 00 00 00 fc ff df 48 8b 3c 24 4c 8b 6c 24 18 4c 8b 64 24 28 e9 7f fc ff ff e8 45 5d fe f6 90 <0f> 0b 90 e9 64 f1 ff ff e8 37 5d fe f6 c6 05 16 e3 84 05 01 90 48
> RSP: 0018:ffffc9001cbbf3d8 EFLAGS: 00010293
> RAX: ffffffff8ac4f7db RBX: 0000000000000000 RCX: ffff88807a275a00
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000000 R08: ffffffff8ac4e8fb R09: 1ffffffff201fa64
> R10: dffffc0000000000 R11: fffffbfff201fa65 R12: ffff88805d942000
> R13: ffff88805d942000 R14: dffffc0000000000 R15: ffff88805d942000
> FS:  0000000000000000(0000) GS:ffff888125096000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000f5045ffc CR3: 0000000032240000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  ipv6_find_idev+0xc2/0x1e0 net/ipv6/addrconf.c:496
>  addrconf_add_dev+0xbe/0x530 net/ipv6/addrconf.c:2560
>  addrconf_dev_config net/ipv6/addrconf.c:3479 [inline]
>  addrconf_init_auto_addrs+0x8f1/0xfe0 net/ipv6/addrconf.c:3567
>  addrconf_notify+0xaff/0x1020 net/ipv6/addrconf.c:3740
>  notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
>  netdev_state_change+0x123/0x1a0 net/core/dev.c:1536

Still has netdev_state_change

#syz fix: "net: hold instance lock during NETDEV_CHANGE"