From: Hyunwoo Kim <v4bel@theori.io>
To: ralf@linux-mips.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com
Cc: v4bel@theori.io, imv4bel@gmail.com, linux-hams@vger.kernel.org,
netdev@vger.kernel.org,
syzbot+caa188bdfc1eeafeb418@syzkaller.appspotmail.com
Subject: [PATCH] netrom: Fix use-after-free caused by accept on already connected socket
Date: Sat, 21 Jan 2023 07:08:59 -0800 [thread overview]
Message-ID: <20230121150859.GA9817@ubuntu> (raw)
If listen() and accept() are called on an AF_NETROM socket that
has already been connect()ed, accept() succeeds in connecting.
This is because nr_accept() dequeues the skb queued in
`sk->sk_receive_queue` in nr_connect().
This causes nr_accept() to allocate and return a sock with the
sk of the parent AF_NETROM socket. And here's where use-after-free
can happen through complex race conditions:
```
cpu0 cpu1
1. socket_2 = socket(AF_NETROM)
listen(socket_2)
accepted_socket = accept(socket_2) // loopback connection with socket_1
2. socket_1 = socket(AF_NETROM)
nr_create() // sk refcount : 1
connect(socket_1) // loopback connection with socket_2
nr_connect()
nr_establish_data_link()
nr_write_internal()
nr_transmit_buffer()
nr_route_frame()
nr_loopback_queue()
nr_loopback_timer()
nr_rx_frame()
nr_process_rx_frame()
nr_state3_machine()
nr_queue_rx_frame()
sock_queue_rcv_skb()
sock_queue_rcv_skb_reason()
__sock_queue_rcv_skb()
__skb_queue_tail(list, skb); // list : sk->sk_receive_queue
3. listen(socket_1)
nr_listen()
uaf_socket = accept(socket_1)
nr_accept()
skb_dequeue(&sk->sk_receive_queue);
4. close(accepted_socket)
nr_release()
nr_write_internal(sk, NR_DISCREQ)
nr_transmit_buffer() // NR_DISCREQ
nr_route_frame()
nr_loopback_queue()
nr_loopback_timer()
nr_rx_frame() // sk : socket_1's sk
nr_process_rx_frame() // NR_STATE_3
nr_state3_machine() // NR_DISCREQ
nr_disconnect()
nr_sk(sk)->state = NR_STATE_0;
5. close(socket_1) // sk refcount : 3
nr_release() // NR_STATE_0
sock_put(sk); // sk refcount : 0
sk_free(sk);
close(uaf_socket)
nr_release()
sock_hold(sk); // UAF
```
KASAN report by syzbot:
```
BUG: KASAN: use-after-free in nr_release+0x66/0x460 net/netrom/af_netrom.c:520
Write of size 4 at addr ffff8880235d8080 by task syz-executor564/5128
CPU: 0 PID: 5128 Comm: syz-executor564 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:306 [inline]
print_report+0x15e/0x461 mm/kasan/report.c:417
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x141/0x190 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
__refcount_add include/linux/refcount.h:193 [inline]
__refcount_inc include/linux/refcount.h:250 [inline]
refcount_inc include/linux/refcount.h:267 [inline]
sock_hold include/net/sock.h:775 [inline]
nr_release+0x66/0x460 net/netrom/af_netrom.c:520
__sock_release+0xcd/0x280 net/socket.c:650
sock_close+0x1c/0x20 net/socket.c:1365
__fput+0x27c/0xa90 fs/file_table.c:320
task_work_run+0x16f/0x270 kernel/task_work.c:179
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xaa8/0x2950 kernel/exit.c:867
do_group_exit+0xd4/0x2a0 kernel/exit.c:1012
get_signal+0x21c3/0x2450 kernel/signal.c:2859
arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6c19e3c9b9
Code: Unable to access opcode bytes at 0x7f6c19e3c98f.
RSP: 002b:00007fffd4ba2ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: 0000000000000116 RBX: 0000000000000003 RCX: 00007f6c19e3c9b9
RDX: 0000000000000318 RSI: 00000000200bd000 RDI: 0000000000000006
RBP: 0000000000000003 R08: 000000000000000d R09: 000000000000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 000055555566a2c0
R13: 0000000000000011 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Allocated by task 5128:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa3/0xb0 mm/kasan/common.c:380
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:968 [inline]
__kmalloc+0x5a/0xd0 mm/slab_common.c:981
kmalloc include/linux/slab.h:584 [inline]
sk_prot_alloc+0x140/0x290 net/core/sock.c:2038
sk_alloc+0x3a/0x7a0 net/core/sock.c:2091
nr_create+0xb6/0x5f0 net/netrom/af_netrom.c:433
__sock_create+0x359/0x790 net/socket.c:1515
sock_create net/socket.c:1566 [inline]
__sys_socket_create net/socket.c:1603 [inline]
__sys_socket_create net/socket.c:1588 [inline]
__sys_socket+0x133/0x250 net/socket.c:1636
__do_sys_socket net/socket.c:1649 [inline]
__se_sys_socket net/socket.c:1647 [inline]
__x64_sys_socket+0x73/0xb0 net/socket.c:1647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Freed by task 5128:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x13b/0x1a0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
__cache_free mm/slab.c:3394 [inline]
__do_kmem_cache_free mm/slab.c:3580 [inline]
__kmem_cache_free+0xcd/0x3b0 mm/slab.c:3587
sk_prot_free net/core/sock.c:2074 [inline]
__sk_destruct+0x5df/0x750 net/core/sock.c:2166
sk_destruct net/core/sock.c:2181 [inline]
__sk_free+0x175/0x460 net/core/sock.c:2192
sk_free+0x7c/0xa0 net/core/sock.c:2203
sock_put include/net/sock.h:1991 [inline]
nr_release+0x39e/0x460 net/netrom/af_netrom.c:554
__sock_release+0xcd/0x280 net/socket.c:650
sock_close+0x1c/0x20 net/socket.c:1365
__fput+0x27c/0xa90 fs/file_table.c:320
task_work_run+0x16f/0x270 kernel/task_work.c:179
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xaa8/0x2950 kernel/exit.c:867
do_group_exit+0xd4/0x2a0 kernel/exit.c:1012
get_signal+0x21c3/0x2450 kernel/signal.c:2859
arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203
__syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
```
To fix this problem, nr_listen() returns -EINVAL for sockets that
successfully nr_connect().
Reported-by: syzbot+caa188bdfc1eeafeb418@syzkaller.appspotmail.com
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
---
net/netrom/af_netrom.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 6f7f4392cffb..dcfa606684d7 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -400,6 +400,11 @@ static int nr_listen(struct socket *sock, int backlog)
struct sock *sk = sock->sk;
lock_sock(sk);
+ if (sock->state == SS_CONNECTED) {
+ release_sock(sk);
+ return -EINVAL;
+ }
+
if (sk->sk_state != TCP_LISTEN) {
memset(&nr_sk(sk)->user_addr, 0, AX25_ADDR_LEN);
sk->sk_max_ack_backlog = backlog;
--
2.25.1
next reply other threads:[~2023-01-21 15:08 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-21 15:08 Hyunwoo Kim [this message]
2023-01-21 15:12 ` [PATCH] netrom: Fix use-after-free caused by accept on already connected socket Hyunwoo Kim
2023-01-23 16:22 ` Kuniyuki Iwashima
2023-01-23 16:22 ` Kuniyuki Iwashima
2023-01-23 16:57 ` Hyunwoo Kim
2023-01-23 17:24 ` Kuniyuki Iwashima
2023-01-23 17:24 ` Kuniyuki Iwashima
2023-01-23 18:22 ` Hyunwoo Kim
2023-01-23 19:27 ` Kuniyuki Iwashima
2023-01-23 19:27 ` Kuniyuki Iwashima
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230121150859.GA9817@ubuntu \
--to=v4bel@theori.io \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=imv4bel@gmail.com \
--cc=kuba@kernel.org \
--cc=linux-hams@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=ralf@linux-mips.org \
--cc=syzbot+caa188bdfc1eeafeb418@syzkaller.appspotmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.