From: Simon Horman <horms@kernel.org>
To: Long Li <longli@microsoft.com>
Cc: Konstantin Taranov <kotaranov@microsoft.com>,
Jakub Kicinski <kuba@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>,
Eric Dumazet <edumazet@google.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,
Haiyang Zhang <haiyangz@microsoft.com>,
"K . Y . Srinivasan" <kys@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
shradhagupta@linux.microsoft.com, ernis@linux.microsoft.com,
stephen@networkplumber.org, shirazsaleem@microsoft.com,
netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org, sdf@fomichev.me, daniel@iogearbox.net,
hawk@kernel.org, ast@kernel.org, john.fastabend@gmail.com
Subject: Re: [PATCH net] net: mana: restore the XDP program pointer when pre-allocation fails
Date: Tue, 8 Sep 2026 10:43:21 +0100 [thread overview]
Message-ID: <20260908094321.GR40544@horms.kernel.org> (raw)
In-Reply-To: <20260904202640.3900685-1-longli@microsoft.com>
On Fri, Sep 04, 2026 at 01:26:40PM -0700, Long Li wrote:
> mana_xdp_set() publishes the new program into apc->bpf_prog before it
> allocates anything, because mana_pre_alloc_rxbufs() sizes the buffers
> from it via mana_get_rxbuf_cfg(). When that allocation fails the
> function returns the error directly, skipping the err_dealloc_rxbuffs
> label which is the only place that restores the previous pointer.
>
> The attach is reported as failed, so the BPF core drops the reference it
> held for the caller and the program can be freed, while apc->bpf_prog
> still points at it. The next consumer of mana_xdp_get() - typically
> mana_chn_setxdp() from mana_alloc_queues() on the following ifup, or
> after a TX timeout reset - then calls bpf_prog_add() on freed memory.
>
> This is reachable from an ordinary "ip link set dev ethX xdp obj ..."
> whenever the per-queue RX buffer pre-allocation cannot be satisfied.
>
> Restore the previous program on that error path.
>
> Fixes: 730ff06d3f5c ("net: mana: Use page pool fragments for RX buffers instead of full pages to improve memory efficiency.")
> Signed-off-by: Long Li <longli@microsoft.com>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-09-08 9:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 20:26 [PATCH net] net: mana: restore the XDP program pointer when pre-allocation fails Long Li
2026-09-08 9:43 ` Simon Horman [this message]
2026-09-10 15:20 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260908094321.GR40544@horms.kernel.org \
--to=horms@kernel.org \
--cc=andrew+netdev@lunn.ch \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=decui@microsoft.com \
--cc=edumazet@google.com \
--cc=ernis@linux.microsoft.com \
--cc=haiyangz@microsoft.com \
--cc=hawk@kernel.org \
--cc=jgg@ziepe.ca \
--cc=john.fastabend@gmail.com \
--cc=kotaranov@microsoft.com \
--cc=kuba@kernel.org \
--cc=kys@microsoft.com \
--cc=leon@kernel.org \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rdma@vger.kernel.org \
--cc=longli@microsoft.com \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=sdf@fomichev.me \
--cc=shirazsaleem@microsoft.com \
--cc=shradhagupta@linux.microsoft.com \
--cc=stephen@networkplumber.org \
--cc=wei.liu@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.