general protection fault in xfrmi_lookup

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    e2a322a0c8ce Merge branch 'net-smc-userspace-breakage-fixes'
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=12087ce9400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb
dashboard link: https://syzkaller.appspot.com/bug?extid=ef5639e6d1435df3a1f1
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ef5639e6d1435df3a1f1@xxxxxxxxxxxxxxxxxxxxxxxxx

RBP: 0000000020000000 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000064 R11: 0000000000000293 R12: 00007f25cc19f6d4
R13: 00000000004c48a4 R14: 00000000004d7b90 R15: 0000000000000004
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: 1 PID: 32654 Comm: syz-executor4 Not tainted 4.19.0-rc6+ #134
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline]
RIP: 0010:net_generic include/net/netns/generic.h:45 [inline]
RIP: 0010:xfrmi_lookup.isra.18+0x11f/0x6c0 net/xfrm/xfrm_interface.c:61
Code: 57 af d3 fa 45 84 ed 0f 84 4c 04 00 00 e8 79 ae d3 fa 48 8d bb 08 1b  
00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 7b 05 00 00 4c 8d 6d 98 48 8b 9b 08 1b 00 00 48
RSP: 0018:ffff880181996878 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000800 RCX: ffffc90009ecc000
RDX: 0000000000000461 RSI: ffffffff86ab2717 RDI: 0000000000002308
RBP: ffff880181996998 R08: ffff88019690c700 R09: 0000000000000000
R10: fffffbfff128759a R11: 0000000000000000 R12: 0000000000000036
R13: 0000000000000000 R14: ffff8801d596dd68 R15: ffffea00000000d0
FS:  00007f25cc19f700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001cc821000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 xfrmi_rcv_cb+0xef/0x9d0 net/xfrm/xfrm_interface.c:256
 xfrm6_rcv_cb+0x220/0x400 net/ipv6/xfrm6_protocol.c:59
 xfrm_rcv_cb net/xfrm/xfrm_input.c:108 [inline]
 xfrm_input+0x8aa/0x3190 net/xfrm/xfrm_input.c:496
 xfrm6_rcv_spi net/ipv6/xfrm6_input.c:31 [inline]
 xfrm6_rcv_tnl+0x168/0x1d0 net/ipv6/xfrm6_input.c:74
 xfrm6_rcv+0x17/0x20 net/ipv6/xfrm6_input.c:81
 xfrm6_esp_rcv+0x1a5/0x3a0 net/ipv6/xfrm6_protocol.c:74
 ip6_input_finish+0x3fc/0x1aa0 net/ipv6/ip6_input.c:383
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip6_input+0xe9/0x600 net/ipv6/ip6_input.c:426
 ip6_mc_input+0x48a/0xd20 net/ipv6/ip6_input.c:503
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ipv6_rcv+0x120/0x640 net/ipv6/ip6_input.c:271
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4891
 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5001
 netif_receive_skb_internal+0x12c/0x620 net/core/dev.c:5104
 napi_frags_finish net/core/dev.c:5642 [inline]
 napi_gro_frags+0x75a/0xc90 net/core/dev.c:5715
 tun_get_user+0x3189/0x4250 drivers/net/tun.c:1923
 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1968
 call_write_iter include/linux/fs.h:1808 [inline]
 do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
 do_iter_write+0x185/0x5f0 fs/read_write.c:959
 vfs_writev+0x1f1/0x360 fs/read_write.c:1004
 do_writev+0x11a/0x310 fs/read_write.c:1039
 __do_sys_writev fs/read_write.c:1112 [inline]
 __se_sys_writev fs/read_write.c:1109 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457431
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 54 b5 fb ff c3 48  
83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48  
89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f25cc19eba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000004a RCX: 0000000000457431
RDX: 0000000000000001 RSI: 00007f25cc19ebf0 RDI: 00000000000000f0
RBP: 0000000020000000 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000064 R11: 0000000000000293 R12: 00007f25cc19f6d4
R13: 00000000004c48a4 R14: 00000000004d7b90 R15: 0000000000000004
Modules linked in:
---[ end trace 803f6dba779493b5 ]---
RIP: 0010:__read_once_size include/linux/compiler.h:188 [inline]
RIP: 0010:net_generic include/net/netns/generic.h:45 [inline]
RIP: 0010:xfrmi_lookup.isra.18+0x11f/0x6c0 net/xfrm/xfrm_interface.c:61
Code: 57 af d3 fa 45 84 ed 0f 84 4c 04 00 00 e8 79 ae d3 fa 48 8d bb 08 1b  
00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 7b 05 00 00 4c 8d 6d 98 48 8b 9b 08 1b 00 00 48
RSP: 0018:ffff880181996878 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000800 RCX: ffffc90009ecc000
RDX: 0000000000000461 RSI: ffffffff86ab2717 RDI: 0000000000002308
RBP: ffff880181996998 R08: ffff88019690c700 R09: 0000000000000000
R10: fffffbfff128759a R11: 0000000000000000 R12: 0000000000000036
R13: 0000000000000000 R14: ffff8801d596dd68 R15: ffffea00000000d0
FS:  00007f25cc19f700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001cc821000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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