[ovs-dev] [PATCH v2] netdev-linux: Ignore TSO packets when TSO is not enabled for userspace

[Eelco Chaudron]

When TSO is disabled from a userspace forwarding datapath perspective,
but TSO has been wrongly enabled on the kernel side, log a warning
message, and drop the packet. With the current implementation,
OVS will crash.

Fixes: 73858f9db ("netdev-linux: Prepend the std packet in the TSO packet")
Signed-off-by: Eelco Chaudron <echaudro at redhat.com>
---
v2: Fixed rx->aux_bufs[i] to allow reuse

 lib/netdev-linux.c |   20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 07ece0c7f..d5e693464 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -1292,14 +1292,28 @@ netdev_linux_batch_rxq_recv_sock(struct netdev_rxq_linux *rx, int mtu,
     for (i = 0; i < retval; i++) {
         struct dp_packet *pkt;
 
-        if (mmsgs[i].msg_len < ETH_HEADER_LEN) {
+        if (mmsgs[i].msg_hdr.msg_flags & MSG_TRUNC
+            || mmsgs[i].msg_len < ETH_HEADER_LEN) {
             struct netdev *netdev_ = netdev_rxq_get_netdev(&rx->up);
             struct netdev_linux *netdev = netdev_linux_cast(netdev_);
 
+            /* The rx->aux_bufs[i] will be re-used next time. */
             dp_packet_delete(buffers[i]);
             netdev->rx_dropped += 1;
-            VLOG_WARN_RL(&rl, "%s: Dropped packet: less than ether hdr size",
-                         netdev_get_name(netdev_));
+            if (mmsgs[i].msg_hdr.msg_flags & MSG_TRUNC) {
+                /* Data is truncated, so the packet is corrupted, and needs
+                 * to be dropped. This can happen if TSO/GRO is enabled in
+                 * the kernel, but not in userspace, i.e. there is no dp
+                 * buffer to store the full packet. */
+                VLOG_WARN_RL(&rl,
+                             "%s: Dropped packet: Too big. GRO/TSO enabled?",
+                             netdev_get_name(netdev_));
+            } else {
+                VLOG_WARN_RL(&rl,
+                             "%s: Dropped packet: less than ether hdr size",
+                             netdev_get_name(netdev_));
+            }
+
             continue;
         }