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Mon, 03 Aug 2026 10:35:45 -0700 (PDT) Received: from devvm29614.prn0.facebook.com ([2a03:2880:ff:54::]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84edbd3a4b6sm3994017b3a.4.2026.08.03.10.35.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Aug 2026 10:35:44 -0700 (PDT) Date: Mon, 3 Aug 2026 10:35:42 -0700 From: Bobby Eshleman To: Mina Almasry Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, kerneljasonxing@gmail.com, kuniyu@google.com, bjorn@kernel.org, jiayuan.chen@linux.dev, kaiyuanz@google.com, willemb@google.com, asml.silence@gmail.com, sdf@fomichev.me, fw@strlen.de, Neal Cardwell , Ralf Lici , Will Deacon Subject: Re: [PATCH net v2 3/3] net: tcp: block standard payload injection into devmem skbs Message-ID: References: <20260803171441.408014-1-almasrymina@google.com> <20260803171441.408014-3-almasrymina@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260803171441.408014-3-almasrymina@google.com> On Mon, Aug 03, 2026 at 05:14:41PM +0000, Mina Almasry wrote: > Protect tcp_sendmsg_locked() from mistakenly appending non-zerocopy > page fragments to unreadable devmem skbs. Create a new segment instead. > > Fixes: bd61848900bff ("net: devmem: Implement TX path") > Cc: Pavel Begunkov > Cc: Stanislav Fomichev > Cc: Bobby Eshleman > Signed-off-by: Mina Almasry > Reviewed-by: Pavel Begunkov > --- > net/ipv4/tcp.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c > index 455441f1b6949..186a36c698798 100644 > --- a/net/ipv4/tcp.c > +++ b/net/ipv4/tcp.c > @@ -1278,6 +1278,11 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) > if (copy > msg_data_left(msg)) > copy = msg_data_left(msg); > > + if (zc != MSG_ZEROCOPY && unlikely(!skb_frags_readable(skb))) { > + tcp_mark_push(tp, skb); > + goto new_segment; > + } > + > if (zc == 0) { > bool merge = true; > int i = skb_shinfo(skb)->nr_frags; > -- > 2.55.0.571.g244d577d93-goog > Reviewed-by: Bobby Eshleman