From: Jakub Kicinski <kuba@kernel.org>
To: jiayuan.chen@linux.dev
Cc: bpf@vger.kernel.org, andrew+netdev@lunn.ch, davem@davemloft.net,
edumazet@google.com, pabeni@redhat.com, ast@kernel.org,
daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com,
sdf@fomichev.me, horms@kernel.org, andrii@kernel.org,
eddyz87@gmail.com, memxor@gmail.com, martin.lau@linux.dev,
song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org,
emil@etsalapatis.com, ihor.solodrai@linux.dev, shuah@kernel.org,
kuniyu@google.com, liuhangbin@gmail.com, mkarsten@uwaterloo.ca,
toke@redhat.com, lorenzo.bianconi@oss.qualcomm.com,
echaudro@redhat.com, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH bpf v3 1/2] bpf, veth: xdp: fix page_pool page leak on skb-backed XDP
Date: Thu, 17 Sep 2026 18:58:14 -0700 [thread overview]
Message-ID: <20260917185814.0f944e78@kernel.org> (raw)
In-Reply-To: <20260918013128.3451350-1-kuba@kernel.org>
On Thu, 17 Sep 2026 18:31:28 -0700 Jakub Kicinski wrote:
> [Severity: High]
> The new flag only overrides mem_type in one direction (towards
> MEM_TYPE_PAGE_POOL), while mem_type is still initialized from the shared
> xdp->rxq->mem.type:
>
> net/core/filter.c:bpf_xdp_shrink_data() {
> enum xdp_mem_type mem_type = xdp->rxq->mem.type;
> ...
> }
>
> The commit message says veth's rq->xdp_rxq.mem "is shared per-queue state"
> that "can be clobbered under a packet still in flight". veth also writes a
> frame's memory type into it and never restores it:
>
> drivers/net/veth.c:veth_xdp_rcv_one() {
> case XDP_TX:
> orig_frame = *frame;
> xdp->rxq->mem.type = frame->mem_type;
> ...
> case XDP_REDIRECT:
> orig_frame = *frame;
> xdp->rxq->mem.type = frame->mem_type;
> }
I probably lost most of the context over the months, but for veth can't
we simply:
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index a3fdf1959b76..14dac44487ba 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -653,6 +653,7 @@ static struct xdp_frame *veth_xdp_rcv_one(struct veth_rq *rq,
xdp_convert_frame_to_buff(frame, xdp);
xdp->rxq = &rq->xdp_rxq;
+ xdp->rxq->mem.type = frame->mem_type;
vxbuf.skb = NULL;
act = bpf_prog_run_xdp(xdp_prog, xdp);
@@ -664,7 +665,6 @@ static struct xdp_frame *veth_xdp_rcv_one(struct veth_rq *rq,
break;
case XDP_TX:
orig_frame = *frame;
- xdp->rxq->mem.type = frame->mem_type;
if (unlikely(veth_xdp_tx(rq, xdp, bq) < 0)) {
trace_xdp_exception(rq->dev, xdp_prog, act);
frame = &orig_frame;
@@ -676,7 +676,6 @@ static struct xdp_frame *veth_xdp_rcv_one(struct veth_rq *rq,
goto xdp_xmit;
case XDP_REDIRECT:
orig_frame = *frame;
- xdp->rxq->mem.type = frame->mem_type;
if (xdp_do_redirect(rq->dev, xdp, xdp_prog)) {
frame = &orig_frame;
stats->rx_drops++;
Local agent digging into the "concurrency" claim says the only
concurrency we can have is with the teardown path where we unregister
the rxq without stopping NAPI (probably deserves a patch in this series)
next prev parent reply other threads:[~2026-09-18 1:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 13:56 [PATCH bpf v3 0/2] net: xdp: fix bpf_xdp_shrink_data() page handling on generic XDP and veth Jiayuan Chen
2026-09-11 13:56 ` [PATCH bpf v3 1/2] bpf, veth: xdp: fix page_pool page leak on skb-backed XDP Jiayuan Chen
2026-09-13 13:05 ` Lorenzo Bianconi
2026-09-14 8:46 ` Jiayuan Chen
2026-09-18 1:31 ` Jakub Kicinski
2026-09-18 1:58 ` Jakub Kicinski [this message]
2026-09-11 13:56 ` [PATCH bpf v3 2/2] selftests/bpf: add xdp_shrink_frags Jiayuan Chen
2026-09-18 1:59 ` [PATCH bpf v3 0/2] net: xdp: fix bpf_xdp_shrink_data() page handling on generic XDP and veth Jakub Kicinski
2026-09-18 2:10 ` Alexei Starovoitov
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=20260917185814.0f944e78@kernel.org \
--to=kuba@kernel.org \
--cc=andrew+netdev@lunn.ch \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=echaudro@redhat.com \
--cc=eddyz87@gmail.com \
--cc=edumazet@google.com \
--cc=emil@etsalapatis.com \
--cc=hawk@kernel.org \
--cc=horms@kernel.org \
--cc=ihor.solodrai@linux.dev \
--cc=jiayuan.chen@linux.dev \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kuniyu@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=liuhangbin@gmail.com \
--cc=lorenzo.bianconi@oss.qualcomm.com \
--cc=martin.lau@linux.dev \
--cc=memxor@gmail.com \
--cc=mkarsten@uwaterloo.ca \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=sdf@fomichev.me \
--cc=shuah@kernel.org \
--cc=song@kernel.org \
--cc=toke@redhat.com \
--cc=yonghong.song@linux.dev \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®