KASAN: use-after-free Read in strp_data_ready

[syzbot]

Hello,

syzkaller hit the following crash on
b9f1f1ce866c28e3d9b86202441b220244754a69
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.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


device lo entered promiscuous mode
==================================================================
BUG: KASAN: use-after-free in strp_data_ready+0x2fb/0x390
net/strparser/strparser.c:394
Read of size 1 at addr ffff8801cebdda50 by task syzkaller825731/2994

CPU: 1 PID: 2994 Comm: syzkaller825731 Not tainted 4.14.0-rc4+ #82
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__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+0x25b/0x340 mm/kasan/report.c:409
__asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
strp_data_ready+0x2fb/0x390 net/strparser/strparser.c:394
psock_data_ready+0x56/0x70 net/kcm/kcmsock.c:353
tcp_data_queue+0x1da8/0x3e50 net/ipv4/tcp_input.c:4672
tcp_rcv_established+0x844/0x18a0 net/ipv4/tcp_input.c:5496
tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1460
tcp_v4_rcv+0x24e5/0x2f80 net/ipv4/tcp_ipv4.c:1721
ip_local_deliver_finish+0x2e2/0xba0 net/ipv4/ip_input.c:216
NF_HOOK include/linux/netfilter.h:249 [inline]
ip_local_deliver+0x1ce/0x6e0 net/ipv4/ip_input.c:257
dst_input include/net/dst.h:465 [inline]
ip_rcv_finish+0x887/0x19a0 net/ipv4/ip_input.c:397
NF_HOOK include/linux/netfilter.h:249 [inline]
ip_rcv+0xc3f/0x1820 net/ipv4/ip_input.c:493
__netif_receive_skb_core+0x1a3e/0x34b0 net/core/dev.c:4477
__netif_receive_skb+0x2c/0x1b0 net/core/dev.c:4542
process_backlog+0x203/0x740 net/core/dev.c:5221
napi_poll net/core/dev.c:5619 [inline]
net_rx_action+0x792/0x1910 net/core/dev.c:5685
__do_softirq+0x29d/0xbb2 kernel/softirq.c:284
do_softirq_own_stack+0x2a/0x40 arch/x86/entry/entry_64.S:957
</IRQ>
do_softirq.part.20+0x14d/0x190 kernel/softirq.c:328
do_softirq kernel/softirq.c:176 [inline]
__local_bh_enable_ip+0x135/0x160 kernel/softirq.c:181
local_bh_enable include/linux/bottom_half.h:31 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:726 [inline]
ip_finish_output2+0x8ad/0x1460 net/ipv4/ip_output.c:231
ip_finish_output+0x85e/0xd10 net/ipv4/ip_output.c:317
NF_HOOK_COND include/linux/netfilter.h:238 [inline]
ip_output+0x1cc/0x860 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:459 [inline]
ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
ip_queue_xmit+0x8c6/0x18e0 net/ipv4/ip_output.c:504
tcp_transmit_skb+0x1ab7/0x3840 net/ipv4/tcp_output.c:1137
tcp_write_xmit+0x663/0x4de0 net/ipv4/tcp_output.c:2341
__tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2513
tcp_send_fin+0x1b0/0xdb0 net/ipv4/tcp_output.c:3058
tcp_close+0xbe0/0xfc0 net/ipv4/tcp.c:2232
inet_release+0xed/0x1c0 net/ipv4/af_inet.c:426
sock_release+0x8d/0x1e0 net/socket.c:597
sock_close+0x16/0x20 net/socket.c:1126
__fput+0x333/0x7f0 fs/file_table.c:210
____fput+0x15/0x20 fs/file_table.c:244
task_work_run+0x199/0x270 kernel/task_work.c:112
exit_task_work include/linux/task_work.h:21 [inline]
do_exit+0x9d2/0x1af0 kernel/exit.c:865


---
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[Eric Biggers]

While unfortunately this bug report was ignored, it seems it was eventually
reported as a slightly different use-after-free ("KASAN: use-after-free Read in
psock_write_space") and was fixed around Jan 25 by commit 581e7226a5d4.
So telling syzbot:

#syz fix: kcm: Only allow TCP sockets to be attached to a KCM mux

- Eric