KASAN: use-after-free Read in strp_work

[syzbot]

Hello,

syzkaller hit the following crash on
ad9a19d003703ae06a6e8efc64cf26a939d9e84d
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.


CC: [da...@davemloft.net ebig...@google.com ge...@linux-m68k.org
john.fa...@gmail.com linux-...@vger.kernel.org
net...@vger.kernel.org t...@quantonium.net xiyou.w...@gmail.com]

==================================================================
BUG: KASAN: use-after-free in do_strp_work net/strparser/strparser.c:431
[inline]
BUG: KASAN: use-after-free in strp_work+0xd6/0xf0
net/strparser/strparser.c:450
Read of size 8 at addr ffff8801c669c548 by task kworker/u4:3/63

CPU: 1 PID: 63 Comm: kworker/u4:3 Not tainted 4.13.0+ #43
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: kstrp strp_work
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:52
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x24e/0x340 mm/kasan/report.c:409
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
do_strp_work net/strparser/strparser.c:431 [inline]
strp_work+0xd6/0xf0 net/strparser/strparser.c:450
process_one_work+0xbfa/0x1bd0 kernel/workqueue.c:2119
worker_thread+0x223/0x1860 kernel/workqueue.c:2253
sctp: [Deprecated]: syz-executor0 (pid 8020) Use of int in max_burst socket
option deprecated.
Use struct sctp_assoc_value instead
sctp: [Deprecated]: syz-executor0 (pid 8020) Use of int in max_burst socket
option deprecated.
Use struct sctp_assoc_value instead
kthread+0x39c/0x470 kernel/kthread.c:231
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Allocated by task 7975:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
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
kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
kmem_cache_alloc+0x12e/0x760 mm/slab.c:3561
kmem_cache_zalloc include/linux/slab.h:656 [inline]
kcm_attach net/kcm/kcmsock.c:1394 [inline]
kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
kcm_ioctl+0x2d1/0x1610 net/kcm/kcmsock.c:1695
sock_do_ioctl+0x65/0xb0 net/socket.c:961
sock_ioctl+0x2c2/0x440 net/socket.c:1058
vfs_ioctl fs/ioctl.c:45 [inline]
do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
SYSC_ioctl fs/ioctl.c:700 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
entry_SYSCALL_64_fastpath+0x1f/0xbe

Freed by task 5:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
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:3503 [inline]
kmem_cache_free+0x77/0x280 mm/slab.c:3763
unreserve_psock+0x5a1/0x780 net/kcm/kcmsock.c:547
kcm_write_msgs+0xbae/0x1b80 net/kcm/kcmsock.c:590
kcm_tx_work+0x2e/0x190 net/kcm/kcmsock.c:731
process_one_work+0xbfa/0x1bd0 kernel/workqueue.c:2119
worker_thread+0x223/0x1860 kernel/workqueue.c:2253
kthread+0x39c/0x470 kernel/kthread.c:231
ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

The buggy address belongs to the object at ffff8801c669c380
which belongs to the cache kcm_psock_cache of size 664
The buggy address is located 456 bytes inside of
664-byte region [ffff8801c669c380, ffff8801c669c618)
The buggy address belongs to the page:
page:ffffea000719a700 count:1 mapcount:0 mapping:ffff8801c669c040 index:0x0
compound_mapcount: 0
flags: 0x200000000008100(slab|head)
raw: 0200000000008100 ffff8801c669c040 0000000000000000 0000000100000009
raw: ffffea00070f99a0 ffff8801d2e14550 ffff8801d2e17b00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801c669c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c669c480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801c669c500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801c669c580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c669c600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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[Dmitry Vyukov]

This happened only once on Sep 12 and there was a bunch of fixed in
kcm and strp, at least we need a fresh report

#syz invalid


On Tue, Oct 31, 2017 at 9:24 AM, syzbot
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