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libvhost-user: add vmsg_set_reply_u64() helper 

The VhostUserMsg request is reused as the reply by message processing
functions.  This is risky since request fields may corrupt the reply if
the vhost-user message handler function forgets to re-initialize them.

Changing this practice would be very invasive but we can introduce a
helper function to make u64 payload replies safe.  This also eliminates
code duplication in message processing functions.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20190626074815.19994-2-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-06-26 08:48:12 +01:00 committed by Michael S. Tsirkin
parent 457cfcccdd
commit db68f4ff06
1 changed files with 13 additions and 13 deletions
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26
contrib/libvhost-user/libvhost-user.c
View File

@ -216,6 +216,15 @@ vmsg_close_fds(VhostUserMsg *vmsg)
}
}
/* Set reply payload.u64 and clear request flags and fd_num */
static void vmsg_set_reply_u64(VhostUserMsg *vmsg, uint64_t val)
{
vmsg->flags = 0; /* defaults will be set by vu_send_reply() */
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->payload.u64 = val;
vmsg->fd_num = 0;
}
/* A test to see if we have userfault available */
static bool
have_userfault(void)
@ -1168,10 +1177,7 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
features |= dev->iface->get_protocol_features(dev);
}
vmsg->payload.u64 = features;
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->fd_num = 0;
vmsg_set_reply_u64(vmsg, features);
return true;
}
@ -1307,17 +1313,14 @@ out:
static bool
vu_set_postcopy_listen(VuDev *dev, VhostUserMsg *vmsg)
{
vmsg->payload.u64 = -1;
vmsg->size = sizeof(vmsg->payload.u64);
if (dev->nregions) {
vu_panic(dev, "Regions already registered at postcopy-listen");
vmsg_set_reply_u64(vmsg, -1);
return true;
}
dev->postcopy_listening = true;
vmsg->flags = VHOST_USER_VERSION | VHOST_USER_REPLY_MASK;
vmsg->payload.u64 = 0; /* Success */
vmsg_set_reply_u64(vmsg, 0);
return true;
}
@ -1332,10 +1335,7 @@ vu_set_postcopy_end(VuDev *dev, VhostUserMsg *vmsg)
DPRINT("%s: Done close\n", __func__);
}
vmsg->fd_num = 0;
vmsg->payload.u64 = 0;
vmsg->size = sizeof(vmsg->payload.u64);
vmsg->flags = VHOST_USER_VERSION | VHOST_USER_REPLY_MASK;
vmsg_set_reply_u64(vmsg, 0);
DPRINT("%s: exit\n", __func__);
return true;
}