Re: [PATCH v3 0/3] net/af_packet: fix MTU handling and add jumbo frame support

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 10 Mar 2026 12:21:19 +0100
Xavier Guillaume <xavier.guillaume@ovhcloud.com> wrote:

> This series fixes two bugs in the af_packet PMD related to frame
> size calculations and buffer safety, then enables jumbo frame
> support by deriving the advertised capabilities from the actual
> TPACKET ring configuration.
> 
> Patch 1 fixes the data size calculation in eth_dev_mtu_set() which
> is too restrictive due to TPACKET2_HDRLEN including sizeof(struct
> sockaddr_ll) even though the sockaddr_ll does not consume frame
> data space. The formula is now consistent with the RX and TX paths.
> 
> Patch 2 adds a bounds check in the RX path to prevent a heap buffer
> overflow when the kernel delivers a packet larger than the mbuf data
> room (e.g. if the kernel interface MTU is raised externally).
> 
> Patch 3 replaces the static max_rx_pktlen (RTE_ETHER_MAX_LEN) and
> adds max_mtu, both derived from the configured TPACKET frame size.
> This enables jumbo frame support when the user specifies a larger
> framesz devarg at vdev creation time. Since the ethdev layer now
> validates mtu <= max_mtu before calling the PMD, the data_size
> bounds check in eth_dev_mtu_set() is converted to RTE_ASSERT().

Applied to next-net