Handle the previously overlooked TCP_ESTABLISHED -> TCP_CLOSING
transition (on VIRTIO_VSOCK_OP_RST), which could race with the connect
loop.
Resetting a socket that is still present in connected_table can lead to
memory corruption. The reporter noted lost transports for in-flight skbs,
and I have reproduced crashes caused by re-insertion into connected_table.
list_add double add: new=, prev=, next=.
kernel BUG at lib/list_debug.c:35!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:__list_add_valid_or_report+0x11f/0x130
Call Trace:
vsock_insert_connected.cold+0xe/0x13
virtio_transport_recv_pkt+0x10e9/0x1460
vsock_loopback_work+0x305/0x480
process_one_work+0xe4c/0x1560
worker_thread+0x4f1/0xd60
kthread+0x36e/0x470
ret_from_fork+0x47b/0x6b0
ret_from_fork_asm+0x1a/0x30
Drop the redundant err=0 and the inaccurate comment above signal_pending().
This fix is supplementary to commit 002541ef650b ("vsock: Ignore
signal/timeout on connect() if already established"). Details under Link.
Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Reported-by: Hyunwoo Kim <[email protected]>
Link: https://lore.kernel.org/netdev/anzT1fREOSyHT99k@v4bel/
Signed-off-by: Michal Luczaj <[email protected]>
---
net/vmw_vsock/af_vsock.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 499e902becfa..adf3f018347e 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1712,7 +1712,6 @@ static int vsock_connect(struct socket *sock, struct
sockaddr_unsized *addr,
long timeout;
DEFINE_WAIT(wait);
- err = 0;
sk = sock->sk;
vsk = vsock_sk(sk);
@@ -1834,23 +1833,22 @@ static int vsock_connect(struct socket *sock, struct
sockaddr_unsized *addr,
timeout = schedule_timeout(timeout);
lock_sock(sk);
- /* Connection established. Whatever happens to socket once we
- * release it, that's not connect()'s concern. No need to go
+ /* Connection was established. Whatever happens to socket once
+ * we release it, that's not connect()'s concern. No need to go
* into signal and timeout handling. Call it a day.
*
* Note that allowing to "reset" an already established socket
* here is racy and insecure.
*/
- if (sk->sk_state == TCP_ESTABLISHED)
- break;
+ if (sk->sk_state == TCP_ESTABLISHED ||
+ sk->sk_state == TCP_CLOSING) {
+ err = 0;
+ goto out_wait;
+ }
/* If connection was _not_ established and a signal/timeout came
* to be, we want the socket's state reset. User space may want
* to retry.
- *
- * sk_state != TCP_ESTABLISHED implies that socket is not on
- * vsock_connected_table. We keep the binding and the transport
- * assigned.
*/
if (signal_pending(current) || timeout == 0) {
err = timeout == 0 ? -ETIMEDOUT :
sock_intr_errno(timeout);
@@ -1874,8 +1872,8 @@ static int vsock_connect(struct socket *sock, struct
sockaddr_unsized *addr,
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
}
- err = sock_error(sk);
- if (err) {
+ if (sk->sk_state != TCP_ESTABLISHED && sk->sk_state != TCP_CLOSING) {
+ err = sock_error(sk);
sk->sk_state = TCP_CLOSE;
sock->state = SS_UNCONNECTED;
}
--
2.55.0
