linux/net/core/stream.c
Shigeru Yoshida cac23b7d76 net: Return error from sk_stream_wait_connect() if sk_wait_event() fails
The following NULL pointer dereference issue occurred:

BUG: kernel NULL pointer dereference, address: 0000000000000000
<...>
RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
RIP: 0010:dccp_write_xmit+0x49/0x140 net/dccp/output.c:356
<...>
Call Trace:
 <TASK>
 dccp_sendmsg+0x642/0x7e0 net/dccp/proto.c:801
 inet_sendmsg+0x63/0x90 net/ipv4/af_inet.c:846
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x83/0xe0 net/socket.c:745
 ____sys_sendmsg+0x443/0x510 net/socket.c:2558
 ___sys_sendmsg+0xe5/0x150 net/socket.c:2612
 __sys_sendmsg+0xa6/0x120 net/socket.c:2641
 __do_sys_sendmsg net/socket.c:2650 [inline]
 __se_sys_sendmsg net/socket.c:2648 [inline]
 __x64_sys_sendmsg+0x45/0x50 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x43/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

sk_wait_event() returns an error (-EPIPE) if disconnect() is called on the
socket waiting for the event. However, sk_stream_wait_connect() returns
success, i.e. zero, even if sk_wait_event() returns -EPIPE, so a function
that waits for a connection with sk_stream_wait_connect() may misbehave.

In the case of the above DCCP issue, dccp_sendmsg() is waiting for the
connection. If disconnect() is called in concurrently, the above issue
occurs.

This patch fixes the issue by returning error from sk_stream_wait_connect()
if sk_wait_event() fails.

Fixes: 419ce133ab ("tcp: allow again tcp_disconnect() when threads are waiting")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reported-by: syzbot+c71bc336c5061153b502@syzkaller.appspotmail.com
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2023-12-15 10:48:51 +00:00

221 lines
5.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* SUCS NET3:
*
* Generic stream handling routines. These are generic for most
* protocols. Even IP. Tonight 8-).
* This is used because TCP, LLC (others too) layer all have mostly
* identical sendmsg() and recvmsg() code.
* So we (will) share it here.
*
* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
* (from old tcp.c code)
* Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
*/
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/net.h>
#include <linux/signal.h>
#include <linux/tcp.h>
#include <linux/wait.h>
#include <net/sock.h>
/**
* sk_stream_write_space - stream socket write_space callback.
* @sk: socket
*
* FIXME: write proper description
*/
void sk_stream_write_space(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
struct socket_wq *wq;
if (__sk_stream_is_writeable(sk, 1) && sock) {
clear_bit(SOCK_NOSPACE, &sock->flags);
rcu_read_lock();
wq = rcu_dereference(sk->sk_wq);
if (skwq_has_sleeper(wq))
wake_up_interruptible_poll(&wq->wait, EPOLLOUT |
EPOLLWRNORM | EPOLLWRBAND);
if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
rcu_read_unlock();
}
}
/**
* sk_stream_wait_connect - Wait for a socket to get into the connected state
* @sk: sock to wait on
* @timeo_p: for how long to wait
*
* Must be called with the socket locked.
*/
int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
struct task_struct *tsk = current;
int done;
do {
int err = sock_error(sk);
if (err)
return err;
if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
return -EPIPE;
if (!*timeo_p)
return -EAGAIN;
if (signal_pending(tsk))
return sock_intr_errno(*timeo_p);
add_wait_queue(sk_sleep(sk), &wait);
sk->sk_write_pending++;
done = sk_wait_event(sk, timeo_p,
!READ_ONCE(sk->sk_err) &&
!((1 << READ_ONCE(sk->sk_state)) &
~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait);
remove_wait_queue(sk_sleep(sk), &wait);
sk->sk_write_pending--;
} while (!done);
return done < 0 ? done : 0;
}
EXPORT_SYMBOL(sk_stream_wait_connect);
/**
* sk_stream_closing - Return 1 if we still have things to send in our buffers.
* @sk: socket to verify
*/
static int sk_stream_closing(const struct sock *sk)
{
return (1 << READ_ONCE(sk->sk_state)) &
(TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
}
void sk_stream_wait_close(struct sock *sk, long timeout)
{
if (timeout) {
DEFINE_WAIT_FUNC(wait, woken_wake_function);
add_wait_queue(sk_sleep(sk), &wait);
do {
if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait))
break;
} while (!signal_pending(current) && timeout);
remove_wait_queue(sk_sleep(sk), &wait);
}
}
EXPORT_SYMBOL(sk_stream_wait_close);
/**
* sk_stream_wait_memory - Wait for more memory for a socket
* @sk: socket to wait for memory
* @timeo_p: for how long
*/
int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
{
int ret, err = 0;
long vm_wait = 0;
long current_timeo = *timeo_p;
DEFINE_WAIT_FUNC(wait, woken_wake_function);
if (sk_stream_memory_free(sk))
current_timeo = vm_wait = get_random_u32_below(HZ / 5) + 2;
add_wait_queue(sk_sleep(sk), &wait);
while (1) {
sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
goto do_error;
if (!*timeo_p)
goto do_eagain;
if (signal_pending(current))
goto do_interrupted;
sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
if (sk_stream_memory_free(sk) && !vm_wait)
break;
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
sk->sk_write_pending++;
ret = sk_wait_event(sk, &current_timeo, READ_ONCE(sk->sk_err) ||
(READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) ||
(sk_stream_memory_free(sk) && !vm_wait),
&wait);
sk->sk_write_pending--;
if (ret < 0)
goto do_error;
if (vm_wait) {
vm_wait -= current_timeo;
current_timeo = *timeo_p;
if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
(current_timeo -= vm_wait) < 0)
current_timeo = 0;
vm_wait = 0;
}
*timeo_p = current_timeo;
}
out:
if (!sock_flag(sk, SOCK_DEAD))
remove_wait_queue(sk_sleep(sk), &wait);
return err;
do_error:
err = -EPIPE;
goto out;
do_eagain:
/* Make sure that whenever EAGAIN is returned, EPOLLOUT event can
* be generated later.
* When TCP receives ACK packets that make room, tcp_check_space()
* only calls tcp_new_space() if SOCK_NOSPACE is set.
*/
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
err = -EAGAIN;
goto out;
do_interrupted:
err = sock_intr_errno(*timeo_p);
goto out;
}
EXPORT_SYMBOL(sk_stream_wait_memory);
int sk_stream_error(struct sock *sk, int flags, int err)
{
if (err == -EPIPE)
err = sock_error(sk) ? : -EPIPE;
if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
send_sig(SIGPIPE, current, 0);
return err;
}
EXPORT_SYMBOL(sk_stream_error);
void sk_stream_kill_queues(struct sock *sk)
{
/* First the read buffer. */
__skb_queue_purge(&sk->sk_receive_queue);
/* Next, the error queue.
* We need to use queue lock, because other threads might
* add packets to the queue without socket lock being held.
*/
skb_queue_purge(&sk->sk_error_queue);
/* Next, the write queue. */
WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
/* Account for returned memory. */
sk_mem_reclaim_final(sk);
WARN_ON_ONCE(sk->sk_wmem_queued);
/* It is _impossible_ for the backlog to contain anything
* when we get here. All user references to this socket
* have gone away, only the net layer knows can touch it.
*/
}
EXPORT_SYMBOL(sk_stream_kill_queues);