general protection fault in inet6_set_link_af

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 202bb015 UPSTREAM: drm: Add DisplayPort colorspace propert..
git tree: android-5.4
console output: https://syzkaller.appspot.com/x/log.txt?x=10f7594ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8afbf421d629f79a
dashboard link: https://syzkaller.appspot.com/bug?extid=a135ad767fedbde53a58
compiler: Android (6032204 based on r370808) clang version 10.0.1 (https://android.googlesource.com/toolchain/llvm-project 6e765c10313d15c02ab29977a82938f66742c3a9)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=178664e9e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104794a1e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a135ad...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): lo: link becomes ready
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 1877 Comm: syz-executor540 Not tainted 5.4.17-syzkaller-00002-g202bb0151929 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:inet6_set_link_af+0x1c3/0xc50 net/ipv6/addrconf.c:5756
Code: 15 fe 48 83 c3 04 48 89 d8 48 c1 e8 03 42 8a 04 28 84 c0 0f 85 b6 08 00 00 0f b6 1b 49 81 c6 e4 01 00 00 4c 89 f0 48 c1 e8 03 <42> 8a 04 28 84 c0 0f 85 b3 08 00 00 41 89 1e eb 75 80 3d 95 26 46
RSP: 0018:ffff8881d34ce9c0 EFLAGS: 00010207
RAX: 000000000000003c RBX: 0000000000000000 RCX: ffff8881d370c9c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8881d34cea78
RBP: ffff8881d34ceb10 R08: ffffffff832d8c29 R09: ffff8881d34cea40
R10: ffffed103a699d51 R11: 0000000000000000 R12: ffff8881d34cea80
R13: dffffc0000000000 R14: 00000000000001e4 R15: 0000000000000000
FS: 0000000001f6a880(0000) GS:ffff8881dba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000004 CR3: 00000001d45a8001 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_setlink+0x2e25/0x3a90 net/core/rtnetlink.c:2677
rtnl_group_changelink net/core/rtnetlink.c:3009 [inline]
__rtnl_newlink net/core/rtnetlink.c:3165 [inline]
rtnl_newlink+0x1240/0x1d50 net/core/rtnetlink.c:3285
rtnetlink_rcv_msg+0x936/0xc20 net/core/rtnetlink.c:5254
netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2477
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5272
netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
netlink_unicast+0x87c/0xa20 net/netlink/af_netlink.c:1328
netlink_sendmsg+0x9a7/0xd40 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:638 [inline]
sock_sendmsg net/socket.c:658 [inline]
____sys_sendmsg+0x56f/0x860 net/socket.c:2298
___sys_sendmsg net/socket.c:2352 [inline]
__sys_sendmsg+0x26a/0x350 net/socket.c:2398
__do_sys_sendmsg net/socket.c:2407 [inline]
__se_sys_sendmsg net/socket.c:2405 [inline]
__x64_sys_sendmsg+0x7f/0x90 net/socket.c:2405
do_syscall_64+0xc0/0x100 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4402e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffdc441f638 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402e9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000008 R09: 00000000004002c8
R10: 0000000000000005 R11: 0000000000000246 R12: 0000000000401b70
R13: 0000000000401c00 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 9477238fbbd1ccd2 ]---
RIP: 0010:inet6_set_link_af+0x1c3/0xc50 net/ipv6/addrconf.c:5756
Code: 15 fe 48 83 c3 04 48 89 d8 48 c1 e8 03 42 8a 04 28 84 c0 0f 85 b6 08 00 00 0f b6 1b 49 81 c6 e4 01 00 00 4c 89 f0 48 c1 e8 03 <42> 8a 04 28 84 c0 0f 85 b3 08 00 00 41 89 1e eb 75 80 3d 95 26 46
RSP: 0018:ffff8881d34ce9c0 EFLAGS: 00010207
RAX: 000000000000003c RBX: 0000000000000000 RCX: ffff8881d370c9c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8881d34cea78
RBP: ffff8881d34ceb10 R08: ffffffff832d8c29 R09: ffff8881d34cea40
R10: ffffed103a699d51 R11: 0000000000000000 R12: ffff8881d34cea80
R13: dffffc0000000000 R14: 00000000000001e4 R15: 0000000000000000
FS: 0000000001f6a880(0000) GS:ffff8881dba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000004 CR3: 00000001d45a8001 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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