From: Paolo Abeni <pabeni@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx # please delay 2 weeks after 6.13-final release Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> Link: https://patch.msgid.link/20241230-net-mptcp-rbuf-fixes-v1-3-8608af434ceb@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/mptcp/protocol.c | 1 + 1 file changed, 1 insertion(+) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -149,6 +149,7 @@ static bool mptcp_try_coalesce(struct so 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; Patches currently in stable-queue which might be from matttbe@xxxxxxxxxx are queue-6.1/mm-kmemleak-fix-upper-boundary-check-for-physical-address-objects.patch queue-6.1/mptcp-handle-fastopen-disconnect-correctly.patch queue-6.1/mptcp-prevent-excessive-coalescing-on-receive.patch queue-6.1/mptcp-consolidate-suboption-status.patch queue-6.1/selftests-mptcp-connect-f-no-reconnect.patch queue-6.1/mptcp-pm-only-set-fullmesh-for-subflow-endp.patch