On Tue, Mar 26, 2024 at 02:39:27PM +0100, 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(+)
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) {
Is rejecting a 0 return value correct? Technically, a 0 return means
a successful write of 0 bytes - but then again, it is unwise to
attempt to send an fd or other auxilliary ddata without at least one
regular byte, so we should not be attempting a write of 0 bytes. So I
guess this one is okay, although I might have used < instead of <=.