From: Paolo Abeni <pabeni@xxxxxxxxxx>
commit ce7356ae35943cc6494cc692e62d51a734062b7d upstream.
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 <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Link: https://patch.msgid.link/02374660836e1b52afc91966b7535c8c5f7bafb0.1731060874.git.pabeni@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
[ Conflicts in protocol.c, because commit f410cbea9f3d ("tcp: annotate
data-races around tp->window_clamp") has not been backported to this
version. The conflict is easy to resolve, because only the context is
different, but not the line to modify. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/mptcp/protocol.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1986,7 +1986,8 @@ static void mptcp_rcv_space_adjust(struc
slow = lock_sock_fast(ssk);
WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf);
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);
}
}
Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are
queue-5.15/mptcp-cope-racing-subflow-creation-in-mptcp_rcv_space_adjust.patch
