linux-kernel - [syzbot] [net?] general protection fault in ip6_mc_clear

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Message-ID: <68409da6.a00a0220.68b4a.0009.GAE@google.com>
Date: Wed, 04 Jun 2025 12:25:26 -0700
From: syzbot <syzbot+cea6d5c85e63d691dfc1@...kaller.appspotmail.com>
To: 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: [syzbot] [net?] general protection fault in ip6_mc_clear_src (2)

Hello,

syzbot found the following issue on:

HEAD commit:    1af80d00e1e0 Merge tag 'slab-for-6.16' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15259282580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c3a43fc2c7a5747d
dashboard link: https://syzkaller.appspot.com/bug?extid=cea6d5c85e63d691dfc1
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/71ae01bedc1a/disk-1af80d00.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e4e400b63650/vmlinux-1af80d00.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ee506a0eb7e1/bzImage-1af80d00.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cea6d5c85e63d691dfc1@...kaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc001fffe000: 0000 [#1] SMP KASAN NOPTI
KASAN: probably user-memory-access in range [0x00000000ffff0000-0x00000000ffff0007]
CPU: 0 UID: 0 PID: 1099 Comm: kworker/u8:6 Not tainted 6.15.0-syzkaller-11802-g1af80d00e1e0 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
RIP: 0010:ip6_mc_clear_src+0x89/0x5a0 net/ipv6/mcast.c:2599
Code: 49 bc 00 00 00 00 00 fc ff df 48 8d 45 10 49 89 c5 48 89 04 24 49 c1 ed 03 4d 01 e5 eb 32 e8 3e 55 88 f7 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 0f 85 80 04 00 00 4c 8b 3b 48 8d 7b 30 48 89 de e8
RSP: 0018:ffffc90004067308 EFLAGS: 00010206
RAX: 000000001fffe000 RBX: 00000000ffff0000 RCX: ffffffff8a33c19b
RDX: ffff888028444880 RSI: ffffffff8a33c122 RDI: 0000000000000005
RBP: ffff88802af2f800 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffed10055e5f02 R14: ffff88802af2f828 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888124765000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000002e5030 CR3: 000000002a0c0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mld_clear_delrec+0xfb/0x640 net/ipv6/mcast.c:826
 ipv6_mc_destroy_dev+0x49/0x690 net/ipv6/mcast.c:2842
 addrconf_ifdown.isra.0+0x13ef/0x1a90 net/ipv6/addrconf.c:4000
 addrconf_notify+0x220/0x19e0 net/ipv6/addrconf.c:3780
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers net/core/dev.c:2282 [inline]
 unregister_netdevice_many_notify+0xf9a/0x26f0 net/core/dev.c:12076
 unregister_netdevice_many net/core/dev.c:12139 [inline]
 unregister_netdevice_queue+0x305/0x3f0 net/core/dev.c:11983
 unregister_netdevice include/linux/netdevice.h:3379 [inline]
 nsim_destroy+0x197/0x5d0 drivers/net/netdevsim/netdev.c:1068
 __nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1428
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline]
 nsim_dev_reload_destroy+0x10a/0x4d0 drivers/net/netdevsim/dev.c:1661
 nsim_dev_reload_down+0x6e/0xd0 drivers/net/netdevsim/dev.c:968
 devlink_reload+0x1a1/0x7c0 net/devlink/dev.c:461
 devlink_pernet_pre_exit+0x1a0/0x2b0 net/devlink/core.c:509
 ops_pre_exit_list net/core/net_namespace.c:162 [inline]
 ops_undo_list+0x187/0xab0 net/core/net_namespace.c:235
 cleanup_net+0x408/0x890 net/core/net_namespace.c:686
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ip6_mc_clear_src+0x89/0x5a0 net/ipv6/mcast.c:2599
Code: 49 bc 00 00 00 00 00 fc ff df 48 8d 45 10 49 89 c5 48 89 04 24 49 c1 ed 03 4d 01 e5 eb 32 e8 3e 55 88 f7 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 0f 85 80 04 00 00 4c 8b 3b 48 8d 7b 30 48 89 de e8
RSP: 0018:ffffc90004067308 EFLAGS: 00010206
RAX: 000000001fffe000 RBX: 00000000ffff0000 RCX: ffffffff8a33c19b
RDX: ffff888028444880 RSI: ffffffff8a33c122 RDI: 0000000000000005
RBP: ffff88802af2f800 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffed10055e5f02 R14: ffff88802af2f828 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888124865000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000404030 CR3: 0000000034f3f000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	49 bc 00 00 00 00 00 	movabs $0xdffffc0000000000,%r12
   7:	fc ff df
   a:	48 8d 45 10          	lea    0x10(%rbp),%rax
   e:	49 89 c5             	mov    %rax,%r13
  11:	48 89 04 24          	mov    %rax,(%rsp)
  15:	49 c1 ed 03          	shr    $0x3,%r13
  19:	4d 01 e5             	add    %r12,%r13
  1c:	eb 32                	jmp    0x50
  1e:	e8 3e 55 88 f7       	call   0xf7885561
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1) <-- trapping instruction
  2f:	0f 85 80 04 00 00    	jne    0x4b5
  35:	4c 8b 3b             	mov    (%rbx),%r15
  38:	48 8d 7b 30          	lea    0x30(%rbx),%rdi
  3c:	48 89 de             	mov    %rbx,%rsi
  3f:	e8                   	.byte 0xe8


---
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