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

[Philippe Mathieu-Daudé]

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 
---
  subprojects/libvhost-user/libvhost-user.c | 5 +
  1 file changed, 5 insertions(+)


Reviewed-by: Philippe Mathieu-Daudé 
Tested-by: Philippe Mathieu-Daudé 

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

[Daniel P . Berrangé]

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 
> ---
>  subprojects/libvhost-user/libvhost-user.c | 5 +
>  1 file changed, 5 insertions(+)

Reviewed-by: Daniel P. Berrangé 


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

[Stefano Garzarella]

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 
---
 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, , 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