[syzbot] [net?] general protection fault in addrconf_add_ifaddr

[syzbot <syzbot+10d145ea96fc91185445@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    8bc251e5d874 Merge tag 'nf-25-04-03' of git://git.kernel.o..
git tree:       net
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14981178580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=24f9c4330e7c0609
dashboard link: https://syzkaller.appspot.com/bug?extid=10d145ea96fc91185445
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=120f023f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10e5c94c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a500d5daba83/disk-8bc251e5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2459c792199a/vmlinux-8bc251e5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/558655fb055e/bzImage-8bc251e5.xz

The issue was bisected to:

commit 8965c160b8f7333df895321c8aa6bad4a7175f2b
Author: Stanislav Fomichev <sdf@fomichev.me>
Date:   Tue Apr 1 16:34:44 2025 +0000

    net: use netif_disable_lro in ipv6_add_dev

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1334423f980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=10b4423f980000
console output: https://syzkaller.appspot.com/x/log.txt?x=1734423f980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+10d145ea96fc91185445@syzkaller.appspotmail.com
Fixes: 8965c160b8f7 ("net: use netif_disable_lro in ipv6_add_dev")

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000198: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000cc0-0x0000000000000cc7]
CPU: 1 UID: 0 PID: 5850 Comm: syz-executor155 Not tainted 6.14.0-syzkaller-12504-g8bc251e5d874 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:netdev_need_ops_lock include/net/netdev_lock.h:30 [inline]
RIP: 0010:netdev_lock_ops include/net/netdev_lock.h:41 [inline]
RIP: 0010:addrconf_add_ifaddr+0x23e/0x590 net/ipv6/addrconf.c:3157
Code: 03 00 00 8b b4 24 c4 00 00 00 48 8b 7c 24 18 e8 18 a3 25 ff 49 89 c5 48 8d 98 c5 0c 00 00 48 89 d8 48 c1 e8 03 48 89 44 24 38 <42> 0f b6 04 20 84 c0 0f 85 03 03 00 00 48 89 5c 24 28 0f b6 1b 31
RSP: 0018:ffffc90003f3fa00 EFLAGS: 00010203
RAX: 0000000000000198 RBX: 0000000000000cc5 RCX: ffff88807bf51e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9ac50c80
RBP: ffffc90003f3fb50 R08: ffffffff905fc777 R09: 1ffffffff20bf8ee
R10: dffffc0000000000 R11: fffffbfff20bf8ef R12: dffffc0000000000
R13: 0000000000000000 R14: 00002000000000c0 R15: 1ffff920007e7f48
FS:  0000555559d6c380(0000) GS:ffff888125099000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000000c2 CR3: 000000003508e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 inet6_ioctl+0x148/0x280 net/ipv6/af_inet6.c:580
 sock_do_ioctl+0x15a/0x490 net/socket.c:1190
 sock_ioctl+0x644/0x900 net/socket.c:1311
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff0337e62e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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:00007ffdf3f7f118 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffdf3f7f2e8 RCX: 00007ff0337e62e9
RDX: 00002000000000c0 RSI: 0000000000008916 RDI: 0000000000000003
RBP: 00007ff033859610 R08: 0000000000000000 R09: 00007ffdf3f7f2e8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffdf3f7f2d8 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:netdev_need_ops_lock include/net/netdev_lock.h:30 [inline]
RIP: 0010:netdev_lock_ops include/net/netdev_lock.h:41 [inline]
RIP: 0010:addrconf_add_ifaddr+0x23e/0x590 net/ipv6/addrconf.c:3157
Code: 03 00 00 8b b4 24 c4 00 00 00 48 8b 7c 24 18 e8 18 a3 25 ff 49 89 c5 48 8d 98 c5 0c 00 00 48 89 d8 48 c1 e8 03 48 89 44 24 38 <42> 0f b6 04 20 84 c0 0f 85 03 03 00 00 48 89 5c 24 28 0f b6 1b 31
RSP: 0018:ffffc90003f3fa00 EFLAGS: 00010203
RAX: 0000000000000198 RBX: 0000000000000cc5 RCX: ffff88807bf51e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff9ac50c80
RBP: ffffc90003f3fb50 R08: ffffffff905fc777 R09: 1ffffffff20bf8ee
R10: dffffc0000000000 R11: fffffbfff20bf8ef R12: dffffc0000000000
R13: 0000000000000000 R14: 00002000000000c0 R15: 1ffff920007e7f48
FS:  0000555559d6c380(0000) GS:ffff888124f99000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004585c0 CR3: 000000003508e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	03 00                	add    (%rax),%eax
   2:	00 8b b4 24 c4 00    	add    %cl,0xc424b4(%rbx)
   8:	00 00                	add    %al,(%rax)
   a:	48 8b 7c 24 18       	mov    0x18(%rsp),%rdi
   f:	e8 18 a3 25 ff       	call   0xff25a32c
  14:	49 89 c5             	mov    %rax,%r13
  17:	48 8d 98 c5 0c 00 00 	lea    0xcc5(%rax),%rbx
  1e:	48 89 d8             	mov    %rbx,%rax
  21:	48 c1 e8 03          	shr    $0x3,%rax
  25:	48 89 44 24 38       	mov    %rax,0x38(%rsp)
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 03 03 00 00    	jne    0x33a
  37:	48 89 5c 24 28       	mov    %rbx,0x28(%rsp)
  3c:	0f b6 1b             	movzbl (%rbx),%ebx
  3f:	31                   	.byte 0x31


---
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