general protection fault in vhost_chr_write_iter

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 1ec8f1f0 Linux 4.14.111
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=175c0abf200000
kernel config: https://syzkaller.appspot.com/x/.config?x=fdadf290ea9fc6f9
dashboard link: https://syzkaller.appspot.com/bug?extid=4846830ad5f7a8b1ac56
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+484683...@syzkaller.appspotmail.com

general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 10423 Comm: syz-executor.5 Not tainted 4.14.111 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff8880a5b725c0 task.stack: ffff88806f858000
RIP: 0010:vhost_del_umem_range drivers/vhost/vhost.c:949 [inline]
RIP: 0010:vhost_process_iotlb_msg drivers/vhost/vhost.c:1020 [inline]
RIP: 0010:vhost_chr_write_iter drivers/vhost/vhost.c:1049 [inline]
RIP: 0010:vhost_chr_write_iter+0x4a9/0x1260 drivers/vhost/vhost.c:1033
RSP: 0018:ffff88806f85fb90 EFLAGS: 00010246
RAX: 0000000000000002 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: ffffffff84a72659 RDI: ffff88806f1c0fc0
RBP: ffff88806f85fcb0 R08: dffffc0000000000 R09: ffffffff88ca4420
R10: ffff88806f85fb80 R11: ffff8880a5b725c0 R12: ffff88806f1c56c0
R13: 0000000020000180 R14: ffff88806f1c0f00 R15: 0000000000000000
FS: 00007f60e7991700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop1' (ffff8880a49277a0): kobject_uevent_env
CR2: 000000000046d920 CR3: 0000000097725000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
kobject: 'loop1' (ffff8880a49277a0): fill_kobj_path: path
= '/devices/virtual/block/loop1'
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
vhost_net_chr_write_iter+0x59/0x70 drivers/vhost/net.c:1360
call_write_iter include/linux/fs.h:1774 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x4ae/0x6c0 fs/read_write.c:482
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xb8/0x180 fs/read_write.c:581
do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4582f9
RSP: 002b:00007f60e7990c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004582f9
RDX: 0000000000000068 RSI: 000000002046df98 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f60e79916d4
R13: 00000000004c7cbd R14: 00000000004dde48 R15: 00000000ffffffff
Code: ff ff 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 9c 0c 00 00 49 8b 8e c0
00 00 00 48 ba 00 00 00 00 00 fc ff df 49 89 cf 48 c1 e9 03 <80> 3c 11 00
0f 85 61 0c 00 00 4d 8b 27 4d 85 e4 0f 84 27 09 00
RIP: vhost_del_umem_range drivers/vhost/vhost.c:949 [inline] RSP:
ffff88806f85fb90
RIP: vhost_process_iotlb_msg drivers/vhost/vhost.c:1020 [inline] RSP:
ffff88806f85fb90
RIP: vhost_chr_write_iter drivers/vhost/vhost.c:1049 [inline] RSP:
ffff88806f85fb90
RIP: vhost_chr_write_iter+0x4a9/0x1260 drivers/vhost/vhost.c:1033 RSP:
ffff88806f85fb90
kobject: 'loop4' (ffff8880a4a1a9e0): kobject_uevent_env
---[ end trace cee32c3048667f99 ]---
kobject: 'loop4' (ffff8880a4a1a9e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'


---
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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 1ec8f1f0 Linux 4.14.111
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1769774b200000

kernel config: https://syzkaller.appspot.com/x/.config?x=fdadf290ea9fc6f9
dashboard link: https://syzkaller.appspot.com/bug?extid=4846830ad5f7a8b1ac56
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15ded6fd200000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=161d1edd200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+484683...@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
audit: type=1400 audit(1555093810.240:36): avc: denied { map } for
pid=7168 comm="syz-executor564" path="/root/syz-executor564431398"
dev="sda1" ino=16484 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
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
Modules linked in:

CPU: 1 PID: 7168 Comm: syz-executor564 Not tainted 4.14.111 #1

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011

task: ffff888091624740 task.stack: ffff888078080000

RIP: 0010:vhost_del_umem_range drivers/vhost/vhost.c:949 [inline]
RIP: 0010:vhost_process_iotlb_msg drivers/vhost/vhost.c:1020 [inline]
RIP: 0010:vhost_chr_write_iter drivers/vhost/vhost.c:1049 [inline]
RIP: 0010:vhost_chr_write_iter+0x4a9/0x1260 drivers/vhost/vhost.c:1033

RSP: 0018:ffff888078087b90 EFLAGS: 00010246

RAX: 0000000000000002 RBX: dffffc0000000000 RCX: 0000000000000000

RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff888074a60240
RBP: ffff888078087cb0 R08: dffffc0000000000 R09: 0000000000000000
R10: ffff888078087b80 R11: ffff888091624740 R12: ffff888074a64940
R13: 0000000000000000 R14: ffff888074a60180 R15: 0000000000000000
FS: 0000000001477880(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000020000080 CR3: 00000000a6f50000 CR4: 00000000001406e0

Call Trace:
vhost_net_chr_write_iter+0x59/0x70 drivers/vhost/net.c:1360
call_write_iter include/linux/fs.h:1774 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x4ae/0x6c0 fs/read_write.c:482
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xb8/0x180 fs/read_write.c:581
do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
entry_SYSCALL_64_after_hwframe+0x42/0xb7

RIP: 0033:0x440209
RSP: 002b:00007ffc0de061c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440209
RDX: 0000000000000068 RSI: 0000000020000280 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401a90
R13: 0000000000401b20 R14: 0000000000000000 R15: 0000000000000000

Code: ff ff 48 89 f9 48 c1 e9 03 80 3c 11 00 0f 85 9c 0c 00 00 49 8b 8e c0
00 00 00 48 ba 00 00 00 00 00 fc ff df 49 89 cf 48 c1 e9 03 <80> 3c 11 00
0f 85 61 0c 00 00 4d 8b 27 4d 85 e4 0f 84 27 09 00
RIP: vhost_del_umem_range drivers/vhost/vhost.c:949 [inline] RSP:

ffff888078087b90

RIP: vhost_process_iotlb_msg drivers/vhost/vhost.c:1020 [inline] RSP:

ffff888078087b90

RIP: vhost_chr_write_iter drivers/vhost/vhost.c:1049 [inline] RSP:

ffff888078087b90

RIP: vhost_chr_write_iter+0x4a9/0x1260 drivers/vhost/vhost.c:1033 RSP:

ffff888078087b90
---[ end trace d220b034738c198e ]---