netdev - [syzbot] [net?] general protection fault in ip6_create_rt

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Message-ID: <6813876c.050a0220.14dd7d.0012.GAE@google.com>
Date: Thu, 01 May 2025 07:38:36 -0700
From: syzbot <syzbot+3182876310f7cd8e31ec@...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_create_rt_rcu

Hello,

syzbot found the following issue on:

HEAD commit:    8bac8898fe39 Merge tag 'mmc-v6.15-rc1' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15e80a70580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ca17f2d2ba38f7a0
dashboard link: https://syzkaller.appspot.com/bug?extid=3182876310f7cd8e31ec
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/77f12ee7bbba/disk-8bac8898.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fdbf21a52748/vmlinux-8bac8898.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab772c5e7344/bzImage-8bac8898.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3182876310f7cd8e31ec@...kaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000021: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
CPU: 0 UID: 0 PID: 12024 Comm: syz.1.1798 Not tainted 6.15.0-rc4-syzkaller-00040-g8bac8898fe39 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:read_pnet include/net/net_namespace.h:409 [inline]
RIP: 0010:dev_net include/linux/netdevice.h:2708 [inline]
RIP: 0010:ip6_create_rt_rcu+0x272/0x590 net/ipv6/route.c:1236
Code: c4 21 9f f7 45 0f b7 e4 e8 4b 27 50 01 49 8d 87 08 01 00 00 48 89 c2 48 89 44 24 08 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 d6 02 00 00 49 8b 87 08 01 00 00 44 89 e1 ba ff
RSP: 0018:ffffc90004c8f580 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff888146bcdb2c RCX: ffffc90004dc2000
RDX: 0000000000000021 RSI: ffffffff8a1c0f3c RDI: 0000000000000001
RBP: ffffc90004c8f6e0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 1ffff92000991eb2 R14: ffff888146bcdb00 R15: 0000000000000000
FS:  00007f0a0a2226c0(0000) GS:ffff8881249e4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c343bf4 CR3: 000000005c49f000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ip6_pol_route_lookup+0xbfb/0x1e10 net/ipv6/route.c:1293
 pol_lookup_func include/net/ip6_fib.h:616 [inline]
 fib6_rule_lookup+0x5e8/0x720 net/ipv6/fib6_rules.c:125
 rt6_lookup+0x16b/0x220 net/ipv6/route.c:1327
 ipv6_sock_ac_join+0x643/0x800 net/ipv6/anycast.c:96
 do_ipv6_setsockopt+0x3684/0x4420 net/ipv6/ipv6_sockglue.c:919
 ipv6_setsockopt+0xcb/0x170 net/ipv6/ipv6_sockglue.c:993
 tcp_setsockopt+0xa4/0x100 net/ipv4/tcp.c:4077
 do_sock_setsockopt+0x221/0x470 net/socket.c:2296
 __sys_setsockopt+0x1a0/0x230 net/socket.c:2321
 __do_sys_setsockopt net/socket.c:2327 [inline]
 __se_sys_setsockopt net/socket.c:2324 [inline]
 __x64_sys_setsockopt+0xbd/0x160 net/socket.c:2324
 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: 0033:0x7f0a0938e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0a0a222038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f0a095b5fa0 RCX: 00007f0a0938e969
RDX: 000000000000001b RSI: 0000000000000029 RDI: 0000000000000005
RBP: 00007f0a09410ab1 R08: 0000000000000014 R09: 0000000000000000
R10: 00002000000000c0 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0a095b5fa0 R15: 00007ffd77acd2b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:read_pnet include/net/net_namespace.h:409 [inline]
RIP: 0010:dev_net include/linux/netdevice.h:2708 [inline]
RIP: 0010:ip6_create_rt_rcu+0x272/0x590 net/ipv6/route.c:1236
Code: c4 21 9f f7 45 0f b7 e4 e8 4b 27 50 01 49 8d 87 08 01 00 00 48 89 c2 48 89 44 24 08 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 d6 02 00 00 49 8b 87 08 01 00 00 44 89 e1 ba ff
RSP: 0018:ffffc90004c8f580 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff888146bcdb2c RCX: ffffc90004dc2000
RDX: 0000000000000021 RSI: ffffffff8a1c0f3c RDI: 0000000000000001
RBP: ffffc90004c8f6e0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 1ffff92000991eb2 R14: ffff888146bcdb00 R15: 0000000000000000
FS:  00007f0a0a2226c0(0000) GS:ffff888124ae4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055eca2d38d40 CR3: 000000005c49f000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 000000000000000c DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	21 9f f7 45 0f b7    	and    %ebx,-0x48f0ba09(%rdi)
   6:	e4 e8                	in     $0xe8,%al
   8:	4b 27                	rex.WXB (bad)
   a:	50                   	push   %rax
   b:	01 49 8d             	add    %ecx,-0x73(%rcx)
   e:	87 08                	xchg   %ecx,(%rax)
  10:	01 00                	add    %eax,(%rax)
  12:	00 48 89             	add    %cl,-0x77(%rax)
  15:	c2 48 89             	ret    $0x8948
  18:	44 24 08             	rex.R and $0x8,%al
  1b:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  22:	fc ff df
  25:	48 c1 ea 03          	shr    $0x3,%rdx
* 29:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2d:	0f 85 d6 02 00 00    	jne    0x309
  33:	49 8b 87 08 01 00 00 	mov    0x108(%r15),%rax
  3a:	44 89 e1             	mov    %r12d,%ecx
  3d:	ba                   	.byte 0xba
  3e:	ff                   	.byte 0xff


---
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