* [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
@ 2021-02-05 14:32 Norbert Slusarek
2021-02-05 17:19 ` Stefano Garzarella
0 siblings, 1 reply; 3+ messages in thread
From: Norbert Slusarek @ 2021-02-05 14:32 UTC (permalink / raw)
To: sgarzare, kuba, alex.popov, eric.dumazet; +Cc: netdev
From: Norbert Slusarek <nslusarek@gmx.net>
Date: Fri, 5 Feb 2021 13:14:05 +0100
Subject: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
A possible locking issue in vsock_connect_timeout() was recognized by
Eric Dumazet which might cause a null pointer dereference in
vsock_transport_cancel_pkt(). This patch assures that
vsock_transport_cancel_pkt() will be called within the lock, so a race
condition won't occur which could result in vsk->transport to be set to NULL.
Fixes: 380feae0def7 ("vsock: cancel packets when failing to connect")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>
---
net/vmw_vsock/af_vsock.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 6894f21dc147..ad7dd9d93b5b 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1243,7 +1243,6 @@ static void vsock_connect_timeout(struct work_struct *work)
{
struct sock *sk;
struct vsock_sock *vsk;
- int cancel = 0;
vsk = container_of(work, struct vsock_sock, connect_work.work);
sk = sk_vsock(vsk);
@@ -1254,11 +1253,9 @@ static void vsock_connect_timeout(struct work_struct *work)
sk->sk_state = TCP_CLOSE;
sk->sk_err = ETIMEDOUT;
sk->sk_error_report(sk);
- cancel = 1;
+ vsock_transport_cancel_pkt(vsk);
}
release_sock(sk);
- if (cancel)
- vsock_transport_cancel_pkt(vsk);
sock_put(sk);
}
--
2.30.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
2021-02-05 14:32 [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout() Norbert Slusarek
@ 2021-02-05 17:19 ` Stefano Garzarella
2021-02-07 0:56 ` Jakub Kicinski
0 siblings, 1 reply; 3+ messages in thread
From: Stefano Garzarella @ 2021-02-05 17:19 UTC (permalink / raw)
To: Norbert Slusarek; +Cc: kuba, alex.popov, eric.dumazet, netdev, David S. Miller
On Fri, Feb 05, 2021 at 03:32:02PM +0100, Norbert Slusarek wrote:
>From: Norbert Slusarek <nslusarek@gmx.net>
>Date: Fri, 5 Feb 2021 13:14:05 +0100
>Subject: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
>
>A possible locking issue in vsock_connect_timeout() was recognized by
>Eric Dumazet which might cause a null pointer dereference in
>vsock_transport_cancel_pkt(). This patch assures that
>vsock_transport_cancel_pkt() will be called within the lock, so a race
>condition won't occur which could result in vsk->transport to be set to NULL.
>
>Fixes: 380feae0def7 ("vsock: cancel packets when failing to connect")
I have a doubt about the tag to use, since until we introduced
transports in commit c0cfa2d8a788 ("vsock: add multi-transports
support") this issue didn't cause many problems.
But it must be said that in the commit 380feae0def7 ("vsock: cancel
packets when failing to connect") the vsock_transport_cancel_pkt() was
called with the lock held in vsock_stream_connect() and without lock in
vsock_connect_timeout(), so maybe this tag is okay.
Anyway, the patch LGTM:
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
>Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
>Signed-off-by: Norbert Slusarek <nslusarek@gmx.net>
>---
> net/vmw_vsock/af_vsock.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index 6894f21dc147..ad7dd9d93b5b 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1243,7 +1243,6 @@ static void vsock_connect_timeout(struct work_struct *work)
> {
> struct sock *sk;
> struct vsock_sock *vsk;
>- int cancel = 0;
>
> vsk = container_of(work, struct vsock_sock, connect_work.work);
> sk = sk_vsock(vsk);
>@@ -1254,11 +1253,9 @@ static void vsock_connect_timeout(struct work_struct *work)
> sk->sk_state = TCP_CLOSE;
> sk->sk_err = ETIMEDOUT;
> sk->sk_error_report(sk);
>- cancel = 1;
>+ vsock_transport_cancel_pkt(vsk);
> }
> release_sock(sk);
>- if (cancel)
>- vsock_transport_cancel_pkt(vsk);
>
> sock_put(sk);
> }
>--
>2.30.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
2021-02-05 17:19 ` Stefano Garzarella
@ 2021-02-07 0:56 ` Jakub Kicinski
0 siblings, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2021-02-07 0:56 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Norbert Slusarek, alex.popov, eric.dumazet, netdev, David S. Miller
On Fri, 5 Feb 2021 18:19:51 +0100 Stefano Garzarella wrote:
> On Fri, Feb 05, 2021 at 03:32:02PM +0100, Norbert Slusarek wrote:
> >From: Norbert Slusarek <nslusarek@gmx.net>
> >Date: Fri, 5 Feb 2021 13:14:05 +0100
> >Subject: [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout()
> >
> >A possible locking issue in vsock_connect_timeout() was recognized by
> >Eric Dumazet which might cause a null pointer dereference in
> >vsock_transport_cancel_pkt(). This patch assures that
> >vsock_transport_cancel_pkt() will be called within the lock, so a race
> >condition won't occur which could result in vsk->transport to be set to NULL.
> >
> >Fixes: 380feae0def7 ("vsock: cancel packets when failing to connect")
>
> I have a doubt about the tag to use, since until we introduced
> transports in commit c0cfa2d8a788 ("vsock: add multi-transports
> support") this issue didn't cause many problems.
>
> But it must be said that in the commit 380feae0def7 ("vsock: cancel
> packets when failing to connect") the vsock_transport_cancel_pkt() was
> called with the lock held in vsock_stream_connect() and without lock in
> vsock_connect_timeout(), so maybe this tag is okay.
>
> Anyway, the patch LGTM:
>
> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Applied, thanks!
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-02-05 14:32 [PATCH] net/vmw_vsock: improve locking in vsock_connect_timeout() Norbert Slusarek
2021-02-05 17:19 ` Stefano Garzarella
2021-02-07 0:56 ` Jakub Kicinski
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