general protection fault in x25_sendmsg

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 7f301cff ethtool: thunder_bgx: use ethtool.h constants for..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=147e1c8f200000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f1e09a9fa2f50f4
dashboard link: https://syzkaller.appspot.com/bug?extid=19ce131cc2c63fabe6b7
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [andrew...@gmail.com da...@davemloft.net
edum...@google.com gre...@linuxfoundation.org linux-...@vger.kernel.org
linu...@vger.kernel.org m...@dev.tdt.de net...@vger.kernel.org
net...@vger.kernel.org]

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+19ce13...@syzkaller.appspotmail.com

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: 30938 Comm: syz-executor.0 Not tainted 5.1.0-rc3+ #129
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:x25_sendmsg+0x8af/0x1360 net/x25/af_x25.c:1205
Code: 83 e6 01 80 3c 02 00 0f 85 91 09 00 00 49 8b 9c 24 90 04 00 00 48 b8
00 00 00 00 00 fc ff df 48 8d 7b 1c 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 49
RSP: 0018:ffff88805e49fba8 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90012af9000
RDX: 0000000000000003 RSI: 0000000000000001 RDI: 000000000000001c
RBP: ffff88805e49fcb0 R08: ffff888095e1a580 R09: 0000000000000002
R10: ffff888095e1ae28 R11: ffff888095e1a580 R12: ffff88809061ea80
R13: ffff8880615a0080 R14: ffff88805e49fd68 R15: ffff88809061ef10
FS: 00007f768d366700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000625208 CR3: 00000000a5af5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xdd/0x130 net/socket.c:661
__sys_sendto+0x262/0x380 net/socket.c:1932
__do_sys_sendto net/socket.c:1944 [inline]
__se_sys_sendto net/socket.c:1940 [inline]
__x64_sys_sendto+0xe1/0x1a0 net/socket.c:1940
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4582b9
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f768d365c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00000000004582b9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 000000000073bf00 R08: 0000000020000140 R09: 0000000000000012
R10: 0000010000000001 R11: 0000000000000246 R12: 00007f768d3666d4
R13: 00000000004c5a26 R14: 00000000004d9de8 R15: 00000000ffffffff
Modules linked in:
---[ end trace b4b00b1bafd3b79c ]---
RIP: 0010:x25_sendmsg+0x8af/0x1360 net/x25/af_x25.c:1205
Code: 83 e6 01 80 3c 02 00 0f 85 91 09 00 00 49 8b 9c 24 90 04 00 00 48 b8
00 00 00 00 00 fc ff df 48 8d 7b 1c 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 49
RSP: 0018:ffff88805e49fba8 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90012af9000
RDX: 0000000000000003 RSI: 0000000000000001 RDI: 000000000000001c
RBP: ffff88805e49fcb0 R08: ffff888095e1a580 R09: 0000000000000002
R10: ffff888095e1ae28 R11: ffff888095e1a580 R12: ffff88809061ea80
R13: ffff8880615a0080 R14: ffff88805e49fd68 R15: ffff88809061ef10
FS: 00007f768d366700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6afdfdf000 CR3: 00000000a5af5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.