From ff825ab2f455299c0c7287550915a8878e2a66e0 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Fri, 8 Nov 2024 11:58:17 +0100 Subject: [PATCH] mptcp: cope racing subflow creation in mptcp_rcv_space_adjust [ Upstream commit ce7356ae35943cc6494cc692e62d51a734062b7d ] Additional active subflows - i.e. created by the in kernel path manager - are included into the subflow list before starting the 3whs. A racing recvmsg() spooling data received on an already established subflow would unconditionally call tcp_cleanup_rbuf() on all the current subflows, potentially hitting a divide by zero error on the newly created ones. Explicitly check that the subflow is in a suitable state before invoking tcp_cleanup_rbuf(). Fixes: c76c6956566f ("mptcp: call tcp_cleanup_rbuf on subflows") Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/02374660836e1b52afc91966b7535c8c5f7bafb0.1731060874.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/mptcp/protocol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index e99ef1e67e95..b8357d7c6b3a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2045,7 +2045,8 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied) slow = lock_sock_fast(ssk); WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf); WRITE_ONCE(tcp_sk(ssk)->window_clamp, window_clamp); - tcp_cleanup_rbuf(ssk, 1); + if (tcp_can_send_ack(ssk)) + tcp_cleanup_rbuf(ssk, 1); unlock_sock_fast(ssk, slow); } }