[PATCH 5.9 248/255] mptcp: provide rmem[0] limit

[Greg Kroah-Hartman]

From: Paolo Abeni <pabeni@xxxxxxxxxx>

[ Upstream commit 989ef49bdf100cc772b3a8737089df36b1ab1e30 ]

The mptcp proto struct currently does not provide the
required limit for forward memory scheduling. Under
pressure sk_rmem_schedule() will unconditionally try
to use such field and will oops.

Address the issue inheriting the tcp limit, as we already
do for the wmem one.

Fixes: 9c3f94e1681b ("mptcp: add missing memory scheduling in the rx path")
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Reviewed-by: Matthieu Baerts <matthieu.baerts@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/37af798bd46f402fb7c79f57ebbdd00614f5d7fa.1604861097.git.pabeni@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@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
@@ -2122,6 +2122,7 @@ static struct proto mptcp_prot = {
 	.memory_pressure	= &tcp_memory_pressure,
 	.stream_memory_free	= mptcp_memory_free,
 	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_wmem),
+	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_rmem),
 	.sysctl_mem	= sysctl_tcp_mem,
 	.obj_size	= sizeof(struct mptcp_sock),
 	.slab_flags	= SLAB_TYPESAFE_BY_RCU,