KASAN: use-after-free Read in __list_add_valid (3)

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
1f07476ec143bbed7bf0b641749783b1094b4c4f (Tue Jan 23 20:45:40 2018 +0000)
Merge tag 'pci-v4.15-fixes-3' of
git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

So far this crash happened 6 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: syzbot+fbbedb...@syzkaller.appspotmail.com
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==================================================================
BUG: KASAN: use-after-free in __list_add_valid+0xb1/0xd0 lib/list_debug.c:23
Read of size 8 at addr ffff8801bb5893d0 by task syz-executor1/28911

CPU: 0 PID: 28911 Comm: syz-executor1 Not tainted 4.15.0-rc9+ #277
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x25b/0x340 mm/kasan/report.c:409
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
__list_add_valid+0xb1/0xd0 lib/list_debug.c:23
__list_add include/linux/list.h:60 [inline]
list_add include/linux/list.h:79 [inline]
__add_wait_queue include/linux/wait.h:156 [inline]
add_wait_queue+0xcf/0x290 kernel/sched/wait.c:30
vhost_poll_func+0x3d/0x50 drivers/vhost/vhost.c:165
poll_wait include/linux/poll.h:46 [inline]
eventfd_poll+0xe8/0x1f0 fs/eventfd.c:123
vhost_poll_start+0x97/0x1c0 drivers/vhost/vhost.c:212
vhost_vring_ioctl+0xe28/0x19b0 drivers/vhost/vhost.c:1556
vhost_net_ioctl+0x9df/0x1910 drivers/vhost/net.c:1320
vfs_ioctl fs/ioctl.c:46 [inline]
do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f33da20dc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f33da20e700 RCX: 0000000000452f19
RDX: 00000000208ffff8 RSI: 000000004008af20 RDI: 0000000000000017
RBP: 0000000000a2f850 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f33da20e9c0 R15: 0000000000000006

Allocated by task 28878:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
__do_kmalloc_node mm/slab.c:3672 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3679
kmalloc_node include/linux/slab.h:541 [inline]
kvmalloc_node+0x64/0xd0 mm/util.c:397
kvmalloc include/linux/mm.h:541 [inline]
vhost_net_open+0x27/0x670 drivers/vhost/net.c:902
misc_open+0x382/0x500 drivers/char/misc.c:154
chrdev_open+0x257/0x730 fs/char_dev.c:417
do_dentry_open+0x667/0xd40 fs/open.c:752
vfs_open+0x107/0x220 fs/open.c:866
do_last fs/namei.c:3379 [inline]
path_openat+0x1151/0x3530 fs/namei.c:3519
do_filp_open+0x25b/0x3b0 fs/namei.c:3554
do_sys_open+0x502/0x6d0 fs/open.c:1059
SYSC_openat fs/open.c:1086 [inline]
SyS_openat+0x30/0x40 fs/open.c:1080
entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 28878:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3488 [inline]
kfree+0xd6/0x260 mm/slab.c:3803
kvfree+0x36/0x60 mm/util.c:416
vhost_net_release+0x159/0x190 drivers/vhost/net.c:1012
__fput+0x327/0x7e0 fs/file_table.c:210
____fput+0x15/0x20 fs/file_table.c:244
task_work_run+0x199/0x270 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162
prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801bb589140
which belongs to the cache kmalloc-65536 of size 65536
The buggy address is located 656 bytes inside of
65536-byte region [ffff8801bb589140, ffff8801bb599140)
The buggy address belongs to the page:
page:ffffea0006ed6000 count:1 mapcount:0 mapping:ffff8801bb589140 index:0x0
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801bb589140 0000000000000000 0000000100000001
raw: ffffea00068b0820 ffffea000693d020 ffff8801dac02500 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801bb589280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801bb589300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801bb589380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801bb589400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801bb589480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[Peter Zijlstra]

[Dmitry Vyukov]

On Thu, Jan 25, 2018 at 10:47 AM, Peter Zijlstra <pet...@infradead.org> wrote:
>
> Not sure why it landed on my desk, lets give it to the vhost people.

Was a bug on our side, now fixed with:
https://github.com/google/syzkaller/commit/1d18b11287c0248782efe867659c17dbdf76e3d5
Next time will be attributed to drivers/vhost/vhost.c

Thanks for rerouting and pointing to the issue.

[Eric Biggers]

No reproducer for this one but I assume it was yet another report of the
vhost_net bug fixed by commit 4cd879515d68:

#syz fix: vhost_net: stop device during reset owner

- Eric