[v4] vhost-user: support any POSIX system (tested on macOS, FreeBSD, OpenBSD)

[PATCH v4 02/12] libvhost-user: fail vu_message_write() if sendmsg() is failing

Stefano Garzarella posted 12 patches 6 months, 3 weeks ago

Diff against v2 v3 v5 v6 v7 v7 v8
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Maintainers: David Hildenbrand <david@redhat.com>, Igor Mammedov <imammedo@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Raphael Norwitz <raphael@enfabrica.net>, Gerd Hoffmann <kraxel@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, Jason Wang <jasowang@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Thomas Huth <thuth@redhat.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Eduardo Habkost <eduardo@habkost.net>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Coiby Xu <Coiby.Xu@gmail.com>, Laurent Vivier <lvivier@redhat.com>

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[PATCH v4 02/12] libvhost-user: fail vu_message_write() if sendmsg() is failing

Posted by Stefano Garzarella 6 months, 3 weeks ago

In vu_message_write() we use sendmsg() to send the message header,
then a write() to send the payload.

If sendmsg() fails we should avoid sending the payload, since we
were unable to send the header.

Discovered before fixing the issue with the previous patch, where
sendmsg() failed on macOS due to wrong parameters, but the frontend
still sent the payload which the backend incorrectly interpreted
as a wrong header.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 subprojects/libvhost-user/libvhost-user.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c
index 22bea0c775..a11afd1960 100644
--- a/subprojects/libvhost-user/libvhost-user.c
+++ b/subprojects/libvhost-user/libvhost-user.c
@@ -639,6 +639,11 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
         rc = sendmsg(conn_fd, &msg, 0);
     } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
 
+    if (rc <= 0) {
+        vu_panic(dev, "Error while writing: %s", strerror(errno));
+        return false;
+    }
+
     if (vmsg->size) {
         do {
             if (vmsg->data) {
-- 
2.45.0

Re: [PATCH v4 02/12] libvhost-user: fail vu_message_write() if sendmsg() is failing

Posted by Philippe Mathieu-Daudé 6 months, 3 weeks ago

On 8/5/24 09:44, Stefano Garzarella wrote:
> In vu_message_write() we use sendmsg() to send the message header,
> then a write() to send the payload.
> 
> If sendmsg() fails we should avoid sending the payload, since we
> were unable to send the header.
> 
> Discovered before fixing the issue with the previous patch, where
> sendmsg() failed on macOS due to wrong parameters, but the frontend
> still sent the payload which the backend incorrectly interpreted
> as a wrong header.
> 
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>   subprojects/libvhost-user/libvhost-user.c | 5 +++++
>   1 file changed, 5 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Re: [PATCH v4 02/12] libvhost-user: fail vu_message_write() if sendmsg() is failing

Posted by Daniel P. Berrangé 6 months, 3 weeks ago

On Wed, May 08, 2024 at 09:44:46AM +0200, Stefano Garzarella wrote:
> In vu_message_write() we use sendmsg() to send the message header,
> then a write() to send the payload.
> 
> If sendmsg() fails we should avoid sending the payload, since we
> were unable to send the header.
> 
> Discovered before fixing the issue with the previous patch, where
> sendmsg() failed on macOS due to wrong parameters, but the frontend
> still sent the payload which the backend incorrectly interpreted
> as a wrong header.
> 
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  subprojects/libvhost-user/libvhost-user.c | 5 +++++
>  1 file changed, 5 insertions(+)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


With regards,
Daniel
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