Bug 2123369
| Summary: | backport "net: virtio_net_hdr_to_skb: count transport header in UFO" | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | suresh kumar <surkumar> |
| Component: | kernel | Assignee: | Ariel Adam <aadam> |
| kernel sub component: | Networking | QA Contact: | Network QE <network-qe> |
| Status: | CLOSED MIGRATED | Docs Contact: | |
| Severity: | medium | ||
| Priority: | unspecified | CC: | jiji, kzhang, sukulkar |
| Version: | 8.6 | Keywords: | MigratedToJIRA |
| Target Milestone: | rc | Flags: | pm-rhel:
mirror+
|
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2023-09-21 13:38:20 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description of problem: With UDP segmentation offload enabled on Guests, big packets gets dropped before reaching Guest VM. Version-Release number of selected component (if applicable): kernel-4.18.0-372.19.1.el8_6 How reproducible: Always Below upstream commit is solving this issue and is tested by customer and also locally. The test kernel was provided to customer over RHEL kernel 4.18.0-372.19.1.el8_6 +++ commit cf9acc90c80ecbee00334aa85d92f4e74014bcff Author: Jonathan Davies <jonathan.davies> Date: Tue Nov 16 17:42:42 2021 +0000 net: virtio_net_hdr_to_skb: count transport header in UFO virtio_net_hdr_to_skb does not set the skb's gso_size and gso_type correctly for UFO packets received via virtio-net that are a little over the GSO size. This can lead to problems elsewhere in the networking stack, e.g. ovs_vport_send dropping over-sized packets if gso_size is not set. This is due to the comparison if (skb->len - p_off > gso_size) not properly accounting for the transport layer header. p_off includes the size of the transport layer header (thlen), so skb->len - p_off is the size of the TCP/UDP payload. gso_size is read from the virtio-net header. For UFO, fragmentation happens at the IP level so does not need to include the UDP header. Hence the calculation could be comparing a TCP/UDP payload length with an IP payload length, causing legitimate virtio-net packets to have lack gso_type/gso_size information. Example: a UDP packet with payload size 1473 has IP payload size 1481. If the guest used UFO, it is not fragmented and the virtio-net header's flags indicate that it is a GSO frame (VIRTIO_NET_HDR_GSO_UDP), with gso_size = 1480 for an MTU of 1500. skb->len will be 1515 and p_off will be 42, so skb->len - p_off = 1473. Hence the comparison fails, and shinfo->gso_size and gso_type are not set as they should be. Instead, add the UDP header length before comparing to gso_size when using UFO. In this way, it is the size of the IP payload that is compared to gso_size. Fixes: 6dd912f82680 ("net: check untrusted gso_size at kernel entry") Signed-off-by: Jonathan Davies <jonathan.davies> Reviewed-by: Willem de Bruijn <willemb> Signed-off-by: David S. Miller <davem> +++ Current workaround is to disable UFO offloading on guest VMs