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From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
To: stable@vger.kernel.org,
gregkh@linuxfoundation.org
Cc: sashal@kernel.org,
MPTCP Upstream <mptcp@lists.linux.dev>,
Paolo Abeni <pabeni@redhat.com>,
Mat Martineau <martineau@kernel.org>,
"Matthieu Baerts (NGI0)" <matttbe@kernel.org>,
Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 5.15.y] mptcp: prevent excessive coalescing on receive
Date: Sun, 9 Feb 2025 18:55:05 +0100
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From: Paolo Abeni <pabeni@redhat.com>
commit 56b824eb49d6258aa0bad09a406ceac3f643cdae upstream.
Currently the skb size after coalescing is only limited by the skb
layout (the skb must not carry frag_list). A single coalesced skb
covering several MSS can potentially fill completely the receive
buffer. In such a case, the snd win will zero until the receive buffer
will be empty again, affecting tput badly.
Fixes: 8268ed4c9d19 ("mptcp: introduce and use mptcp_try_coalesce()")
Cc: stable@vger.kernel.org # please delay 2 weeks after 6.13-final release
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241230-net-mptcp-rbuf-fixes-v1-3-8608af434=
ceb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Notes:
- We asked to delay the patch. There were no conflicts.
---
net/mptcp/protocol.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f337dd3323a0..c6a11d6df516 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -133,6 +133,7 @@ static bool mptcp_try_coalesce(struct sock *sk, struct =
sk_buff *to,
int delta;
=20
if (MPTCP_SKB_CB(from)->offset ||
+ ((to->len + from->len) > (sk->sk_rcvbuf >> 3)) ||
!skb_try_coalesce(to, from, &fragstolen, &delta))
return false;
=20
--=20
2.47.1