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SubjectKASAN: slab-out-of-bounds Read in vmx_vcpu_run

syzbot found the following crash on:

HEAD commit: 036db8bd9637 Merge branch 'for-4.17-fixes' of git://
git tree: upstream
console output:
kernel config:
dashboard link:
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:

BUG: KASAN: slab-out-of-bounds in msr_write_intercepted
arch/x86/kvm/vmx.c:2126 [inline]
BUG: KASAN: slab-out-of-bounds in vmx_vcpu_run+0x2379/0x25f0
Read of size 8 at addr ffff8801d3efc840 by task syz-executor1/11848

CPU: 1 PID: 11848 Comm: syz-executor1 Not tainted 4.17.0-rc4+ #39
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
msr_write_intercepted arch/x86/kvm/vmx.c:2126 [inline]
vmx_vcpu_run+0x2379/0x25f0 arch/x86/kvm/vmx.c:9869

Allocated by task 11848:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
kmalloc include/linux/slab.h:512 [inline]
kzalloc include/linux/slab.h:701 [inline]
tcp_sendmsg_fastopen net/ipv4/tcp.c:1145 [inline]
tcp_sendmsg_locked+0x2ff7/0x3ee0 net/ipv4/tcp.c:1209
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1447
inet_sendmsg+0x19f/0x690 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:629 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:639
__sys_sendto+0x3d7/0x670 net/socket.c:1789
__do_sys_sendto net/socket.c:1801 [inline]
__se_sys_sendto net/socket.c:1797 [inline]
__x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287

Freed by task 2388:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xd9/0x260 mm/slab.c:3813
inotify_free_event+0x15/0x20 fs/notify/inotify/inotify_fsnotify.c:182
fsnotify_destroy_event.part.1+0x1a8/0x270 fs/notify/notification.c:87
fsnotify_destroy_event+0x69/0x80 fs/notify/notification.c:74
inotify_read+0x5a8/0x9b0 fs/notify/inotify/inotify_user.c:246
__vfs_read+0x10f/0xa50 fs/read_write.c:416
vfs_read+0x17f/0x3d0 fs/read_write.c:452
ksys_read+0xf9/0x250 fs/read_write.c:578
__do_sys_read fs/read_write.c:588 [inline]
__se_sys_read fs/read_write.c:586 [inline]
__x64_sys_read+0x73/0xb0 fs/read_write.c:586
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287

The buggy address belongs to the object at ffff8801d3efc800
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 0 bytes to the right of
64-byte region [ffff8801d3efc800, ffff8801d3efc840)
The buggy address belongs to the page:
page:ffffea00074fbf00 count:1 mapcount:0 mapping:ffff8801d3efc000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d3efc000 0000000000000000 0000000100000020
raw: ffffea00076687a0 ffffea000766e660 ffff8801da800340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d3efc700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8801d3efc780: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> ffff8801d3efc800: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
ffff8801d3efc880: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff8801d3efc900: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

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