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[6.1.y,2/2] mptcp: prevent excessive coalescing on receive

Message ID 20250209174828.3397229-6-matttbe@kernel.org (mailing list archive)
State Mainlined, archived
Delegated to: Matthieu Baerts
Headers show
Series mptcp: pm: only set fullmesh for subflow endp (and more) | expand

Commit Message

Matthieu Baerts Feb. 9, 2025, 5:48 p.m. UTC 
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-v1-3-8608af434ceb@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/protocol.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 0848e63bac65..82eaf20268e4 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -149,6 +149,7 @@  static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
 	int delta;
 
 	if (MPTCP_SKB_CB(from)->offset ||
+	    ((to->len + from->len) > (sk->sk_rcvbuf >> 3)) ||
 	    !skb_try_coalesce(to, from, &fragstolen, &delta))
 		return false;