general protection fault in tcp_sendmsg_locked

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: e2cd24b6 Linux 4.14.143
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15430de6600000
kernel config: https://syzkaller.appspot.com/x/.config?x=dcb6107bcdc0039
dashboard link: https://syzkaller.appspot.com/bug?extid=398480e87696bf4d85a1
compiler: gcc (GCC) 9.0.0 20181231 (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+398480...@syzkaller.appspotmail.com

audit: type=1400 audit(1568113790.224:40): avc: denied { setopt } for
pid=6990 comm="syz-executor.0"
scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 6995 Comm: syz-executor.0 Not tainted 4.14.143 #0
kobject: 'loop4' (ffff8880a4aa29a0): kobject_uevent_env
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880652b42c0 task.stack: ffff8880652b8000
RIP: 0010:tcp_sendmsg_locked+0x50e/0x3200 net/ipv4/tcp.c:1281
RSP: 0018:ffff8880652bf9b0 EFLAGS: 00010206
kobject: 'loop4' (ffff8880a4aa29a0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
RAX: 0000000000000012 RBX: 0000000000000000 RCX: ffffc90005e2d000
RDX: 000000000000011c RSI: ffffffff85240c94 RDI: 0000000000000090
RBP: ffff8880652bfb48 R08: ffff8880652b42c0 R09: 0000000000000001
R10: 0000000000000000 R11: ffff8880652b42c0 R12: dffffc0000000000
kobject: 'loop0' (ffff8880a492ae60): kobject_uevent_env
R13: ffff888093ecf540 R14: ffff8880652bfc28 R15: ffff88806818ac00
FS: 00007f1e9f022700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000b4b340 CR3: 0000000081029000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kobject: 'loop0' (ffff8880a492ae60): fill_kobj_path: path
= '/devices/virtual/block/loop0'
protocol 88fb is buggy, dev hsr_slave_0
tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457
inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762
protocol 88fb is buggy, dev hsr_slave_1
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xce/0x110 net/socket.c:656
sock_write_iter+0x21d/0x390 net/socket.c:925
kobject: 'loop0' (ffff8880a492ae60): kobject_uevent_env
call_write_iter include/linux/fs.h:1777 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x4a7/0x6b0 fs/read_write.c:482
kobject: 'loop0' (ffff8880a492ae60): fill_kobj_path: path
= '/devices/virtual/block/loop0'
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xfd/0x230 fs/read_write.c:582
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
kobject: 'loop4' (ffff8880a4aa29a0): kobject_uevent_env
RIP: 0033:0x4598e9
RSP: 002b:00007f1e9f021c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004598e9
RDX: 00000000fffffffe RSI: 0000000020000380 RDI: 0000000000000008
kobject: 'loop4' (ffff8880a4aa29a0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1e9f0226d4
R13: 00000000004c5e50 R14: 00000000004e0380 R15: 00000000ffffffff
Code: d5
kobject: 'loop0' (ffff8880a492ae60): kobject_uevent_env
38
kobject: 'loop0' (ffff8880a492ae60): fill_kobj_path: path
= '/devices/virtual/block/loop0'
fc 4d 85 ed 0f 84 40 08 00 00
audit: type=1400 audit(1568113790.224:41): avc: denied { ioctl } for
pid=6990 comm="syz-executor.0" path="socket:[26697]" dev="sockfs" ino=26697
ioctlcmd=0x89e2 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
e8 dc d5 38 fc 8b 85 78 ff ff
kobject: 'loop5' (ffff8880a4af32a0): kobject_uevent_env
ff 48 8d bb 90 00 00 00 89 85 50 ff ff ff 48 89 f8 48 c1 e8 03
kobject: 'loop5' (ffff8880a4af32a0): fill_kobj_path: path
= '/devices/virtual/block/loop5'
<42> 0f b6 04 20 84 c0 74 06 0f 8e 4a 25 00 00 f6 83 90 00 00 00
RIP: tcp_sendmsg_locked+0x50e/0x3200 net/ipv4/tcp.c:1281 RSP:
ffff8880652bf9b0
---[ end trace b691269650153889 ]---


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[syzbot]

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