From: Stanislav Fomichev <stfomichev@gmail.com>
To: "Rao, Nikhil" <nikhirao@amd.com>
Cc: magnus.karlsson@intel.com, maciej.fijalkowski@intel.com,
sdf@fomichev.me, netdev@vger.kernel.org
Subject: Re: net/xdp: Potential issue with xp_aligned_validate_desc() in multi-buffer packets
Date: Tue, 3 Feb 2026 18:03:37 -0800 [thread overview]
Message-ID: <aYKo-YeGpsl8ngeK@mini-arch> (raw)
In-Reply-To: <c4b5955a-8ec6-47ac-913d-4a959e0b477e@amd.com>
On 02/03, Rao, Nikhil wrote:
> Hi XDP maintainers,
>
> I have noticed a potential issue with multi-buffer packet support in the
> xp_aligned_validate_desc() function in net/xdp/xsk_queue.h.
>
> In xp_aligned_validate_desc(), the validation always adjusts the address
> and length by pool->tx_metadata_len:
>
> u64 addr = desc->addr - pool->tx_metadata_len;
> u64 len = desc->len + pool->tx_metadata_len;
>
> However, in multi-buffer XDP packets, only the first descriptor contains
> TX metadata. Subsequent descriptors do not have
> metadata and should not be validated with this adjustment.
>
> This causes validation failures for the 2nd buffer onward in
> multi-buffer packets when TX metadata is enabled.
>
> The same issue exists in xp_unaligned_validate_desc() as well.
>
> I'm happy to submit a patch if this is indeed a bug. Please let me know
> your thoughts.
I think your assessment is correct. Can you try to extend
prog_tests/xdp_metadata.c to send a mbuf packet? I don't think we have
any real test coverage for the metadata+mbuf..
prev parent reply other threads:[~2026-02-04 2:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-03 19:58 net/xdp: Potential issue with xp_aligned_validate_desc() in multi-buffer packets Rao, Nikhil
2026-02-04 2:03 ` Stanislav Fomichev [this message]
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