On 4/13/2017 10:21 AM, Yuanhan Liu wrote:
On Thu, Apr 13, 2017 at 10:18:43AM +0800, Tan, Jianfeng wrote:
On 4/13/2017 9:58 AM, Yuanhan Liu wrote:
On Fri, Apr 07, 2017 at 07:57:40AM +0000, Jianfeng Tan wrote:
After the introduction of vhost MTU, VIRTIO_NET_F_MTU is enabled
by default. However, virtio-user vtpci does not support to get
MTU from device yet, i.e., vtpci_read_dev_config(MTU) fails.
Plus, struct virtio_net_config is defined as a uninitialized
variable, and could be different values in
virtio_negotiate_features() and virtio_init_device().
In some cases, it passes the check in virtio_negotiate_features()
but fails the check in virtio_init_device(). As a result,
virtio-user canno be initialized.
To fix it, (1) accessing uninitialized variable is not a good
practice, so initialize it as zero; (2) explicitly disable MTU
feature in virtio-user.
Fixes: 49d26d9e3f47 ("net/virtio: support MTU feature")
Cc: Maxime Coquelin <maxime.coque...@redhat.com>
Cc: Yuanhan Liu <yuanhan....@linux.intel.com>
Signed-off-by: Jianfeng Tan <jianfeng....@intel.com>
---
drivers/net/virtio/virtio_ethdev.c | 4 ++--
drivers/net/virtio/virtio_user/virtio_user_dev.c | 6 ++++++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio/virtio_ethdev.c
b/drivers/net/virtio/virtio_ethdev.c
index 78cb3e8..4c43784 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1163,7 +1163,7 @@ virtio_negotiate_features(struct virtio_hw *hw, uint64_t
req_features)
/* If supported, ensure MTU value is valid before acknowledging it. */
if (host_features & req_features & (1ULL << VIRTIO_NET_F_MTU)) {
- struct virtio_net_config config;
+ struct virtio_net_config config = {0};
virtio-user does not support the MTU feature, this patch should not be
reached. The virtio-user feature negotiation should be broken.
--yliu
Yes, it will not come to here anyway. But some static code analyzer might
report this as an error: there's chance to read uninitialized variable.
If so, fix it in another patch, with the detailed (and real) errors in
the commit log.
OK, I'll drop this fix from this patch.
