Re: general protection fault in ip6_dst_lookup_tail (2)

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    07c3bbdb samples: bpf: print a warning about headers_install
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14424e2ea00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b7b54c66298f8420
dashboard link: https://syzkaller.appspot.com/bug?extid=58d8f704b86e4e3fb4d3
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=117f50e1a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+58d8f704b86e4e3fb4d3@xxxxxxxxxxxxxxxxxxxxxxxxx

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: 14003 Comm: syz-executor.4 Not tainted 5.2.0-rc2+ #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:ip6_route_get_saddr include/net/ip6_route.h:120 [inline]
RIP: 0010:ip6_dst_lookup_tail+0xf0e/0x1b30 net/ipv6/ip6_output.c:1032
Code: e6 07 e8 75 66 55 fb 48 85 db 0f 84 83 08 00 00 e8 67 66 55 fb 48 8d  
7b 7c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48  
89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 07
RSP: 0018:ffff888079027480 EFLAGS: 00010a07
RAX: dffffc0000000000 RBX: ff8880990716c000 RCX: 0000000000000000
RDX: 1ff1101320e2d80f RSI: ffffffff861b3f59 RDI: ff8880990716c07c
RBP: ffff8880790275d8 R08: ffff8880855b43c0 R09: ffffed1015d26be8
R10: ffffed1015d26be7 R11: ffff8880ae935f3b R12: ffff888079027740
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888079027768
FS:  00007f7158009700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd85cf4eb8 CR3: 00000000a96aa000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ip6_dst_lookup_flow+0xa8/0x220 net/ipv6/ip6_output.c:1155
 tcp_v6_connect+0xda3/0x20a0 net/ipv6/tcp_ipv6.c:282
 __inet_stream_connect+0x834/0xe90 net/ipv4/af_inet.c:659
 tcp_sendmsg_fastopen net/ipv4/tcp.c:1143 [inline]
 tcp_sendmsg_locked+0x2318/0x3920 net/ipv4/tcp.c:1185
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1419
 inet_sendmsg+0x141/0x5d0 net/ipv4/af_inet.c:802
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:671
 ___sys_sendmsg+0x803/0x920 net/socket.c:2292
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2330
 __do_sys_sendmsg net/socket.c:2339 [inline]
 __se_sys_sendmsg net/socket.c:2337 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2337
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7158008c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459279
RDX: 0000000020008844 RSI: 0000000020000240 RDI: 0000000000000005
RBP: 000000000075bfc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f71580096d4
R13: 00000000004c6ccc R14: 00000000004dbb30 R15: 00000000ffffffff
Modules linked in:
---[ end trace c968f232eacd4c70 ]---
RIP: 0010:ip6_route_get_saddr include/net/ip6_route.h:120 [inline]
RIP: 0010:ip6_dst_lookup_tail+0xf0e/0x1b30 net/ipv6/ip6_output.c:1032
Code: e6 07 e8 75 66 55 fb 48 85 db 0f 84 83 08 00 00 e8 67 66 55 fb 48 8d  
7b 7c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48  
89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 07
RSP: 0018:ffff888079027480 EFLAGS: 00010a07
RAX: dffffc0000000000 RBX: ff8880990716c000 RCX: 0000000000000000
RDX: 1ff1101320e2d80f RSI: ffffffff861b3f59 RDI: ff8880990716c07c
RBP: ffff8880790275d8 R08: ffff8880855b43c0 R09: ffffed1015d26be8
R10: ffffed1015d26be7 R11: ffff8880ae935f3b R12: ffff888079027740
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888079027768
FS:  00007f7158009700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000015523b8 CR3: 00000000a96aa000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400