From: Mina Almasry <almasrymina@google.com>
Cc: Mina Almasry <almasrymina@google.com>,
Pavel Begunkov <asml.silence@gmail.com>,
Stanislav Fomichev <sdf@fomichev.me>,
Bobby Eshleman <bobbyeshleman@gmail.com>,
Eric Dumazet <edumazet@google.com>,
Neal Cardwell <ncardwell@google.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Kaiyuan Zhang <kaiyuanz@google.com>,
"open list:NETWORKING [TCP]" <netdev@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: [PATCH net v1 3/3] net: tcp: block standard payload injection into devmem skbs
Date: Sat, 1 Aug 2026 12:52:21 +0000 [thread overview]
Message-ID: <20260801125308.1342897-3-almasrymina@google.com> (raw)
In-Reply-To: <20260801125308.1342897-1-almasrymina@google.com>
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 <asml.silence@gmail.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Bobby Eshleman <bobbyeshleman@gmail.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
---
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
prev parent reply other threads:[~2026-08-01 12:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-01 12:52 [PATCH net v1 1/3] net: core: propagate unreadable flag in skb_zerocopy Mina Almasry
2026-08-01 12:52 ` [PATCH net v1 2/3] net: devmem: return EMSGSIZE on type mismatch Mina Almasry
2026-08-01 12:52 ` Mina Almasry [this message]
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