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authorMichael S. Tsirkin <mst@redhat.com>2018-01-08 19:47:11 +0200
committerMichael S. Tsirkin <mst@redhat.com>2018-01-18 21:52:39 +0200
commit69aff030643c1616474458cf7e19fc15a5f8f462 (patch)
treea4bfd1d96c0cc87889b35f75f14dd73d2a45f673 /hw/virtio
parent24e34754eb78064abafd3f9a59bb35a0e2bcf406 (diff)
downloadqemu-69aff030643c1616474458cf7e19fc15a5f8f462.tar.gz
vhost-user: fix misaligned access to payload
We currently take a pointer to a misaligned field of a packed structure. clang reports this as a build warning. A fix is to keep payload in a separate structure, and access is it from there using a vectored write. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'hw/virtio')
-rw-r--r--hw/virtio/vhost-user.c39
1 files changed, 24 insertions, 15 deletions
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 6ac3610996..7930fd85fc 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -652,33 +652,34 @@ static void slave_read(void *opaque)
{
struct vhost_dev *dev = opaque;
struct vhost_user *u = dev->opaque;
- VhostUserMsg msg = { 0, };
+ VhostUserHeader hdr = { 0, };
+ VhostUserPayload payload = { 0, };
int size, ret = 0;
/* Read header */
- size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE);
+ size = read(u->slave_fd, &hdr, VHOST_USER_HDR_SIZE);
if (size != VHOST_USER_HDR_SIZE) {
error_report("Failed to read from slave.");
goto err;
}
- if (msg.hdr.size > VHOST_USER_PAYLOAD_SIZE) {
+ if (hdr.size > VHOST_USER_PAYLOAD_SIZE) {
error_report("Failed to read msg header."
- " Size %d exceeds the maximum %zu.", msg.hdr.size,
+ " Size %d exceeds the maximum %zu.", hdr.size,
VHOST_USER_PAYLOAD_SIZE);
goto err;
}
/* Read payload */
- size = read(u->slave_fd, &msg.payload, msg.hdr.size);
- if (size != msg.hdr.size) {
+ size = read(u->slave_fd, &payload, hdr.size);
+ if (size != hdr.size) {
error_report("Failed to read payload from slave.");
goto err;
}
- switch (msg.hdr.request) {
+ switch (hdr.request) {
case VHOST_USER_SLAVE_IOTLB_MSG:
- ret = vhost_backend_handle_iotlb_msg(dev, &msg.payload.iotlb);
+ ret = vhost_backend_handle_iotlb_msg(dev, &payload.iotlb);
break;
case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :
ret = vhost_user_slave_handle_config_change(dev);
@@ -692,15 +693,23 @@ static void slave_read(void *opaque)
* REPLY_ACK feature handling. Other reply types has to be managed
* directly in their request handlers.
*/
- if (msg.hdr.flags & VHOST_USER_NEED_REPLY_MASK) {
- msg.hdr.flags &= ~VHOST_USER_NEED_REPLY_MASK;
- msg.hdr.flags |= VHOST_USER_REPLY_MASK;
+ if (hdr.flags & VHOST_USER_NEED_REPLY_MASK) {
+ struct iovec iovec[2];
- msg.payload.u64 = !!ret;
- msg.hdr.size = sizeof(msg.payload.u64);
- size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.hdr.size);
- if (size != VHOST_USER_HDR_SIZE + msg.hdr.size) {
+ hdr.flags &= ~VHOST_USER_NEED_REPLY_MASK;
+ hdr.flags |= VHOST_USER_REPLY_MASK;
+
+ payload.u64 = !!ret;
+ hdr.size = sizeof(payload.u64);
+
+ iovec[0].iov_base = &hdr;
+ iovec[0].iov_len = VHOST_USER_HDR_SIZE;
+ iovec[1].iov_base = &payload;
+ iovec[1].iov_len = hdr.size;
+
+ size = writev(u->slave_fd, iovec, ARRAY_SIZE(iovec));
+ if (size != VHOST_USER_HDR_SIZE + hdr.size) {
error_report("Failed to send msg reply to slave.");
goto err;
}