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authorPaolo Abeni <pabeni@redhat.com>2023-09-16 13:52:45 +0300
committerDavid S. Miller <davem@davemloft.net>2023-09-18 14:47:55 +0300
commit6bec041147a2a64a490d1f813e8a004443061b38 (patch)
tree38cc2760598232c98535644e7ae27989d41dec54 /net
parent8a47558a8c7329e91a58d89c55fc9b8c5beae76b (diff)
downloadlinux-6bec041147a2a64a490d1f813e8a004443061b38.tar.xz
mptcp: fix bogus receive window shrinkage with multiple subflows
In case multiple subflows race to update the mptcp-level receive window, the subflow losing the race should use the window value provided by the "winning" subflow to update it's own tcp-level rcv_wnd. To such goal, the current code bogusly uses the mptcp-level rcv_wnd value as observed before the update attempt. On unlucky circumstances that may lead to TCP-level window shrinkage, and stall the other end. Address the issue feeding to the rcv wnd update the correct value. Fixes: f3589be0c420 ("mptcp: never shrink offered window") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/427 Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/mptcp/options.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index c254accb14de..cd15ec73073e 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1269,12 +1269,13 @@ static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th)
if (rcv_wnd == rcv_wnd_old)
break;
- if (before64(rcv_wnd_new, rcv_wnd)) {
+
+ rcv_wnd_old = rcv_wnd;
+ if (before64(rcv_wnd_new, rcv_wnd_old)) {
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE);
goto raise_win;
}
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT);
- rcv_wnd_old = rcv_wnd;
}
return;
}