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sctp: move sk_route_caps check and set into sctp_outq_flush_transports 

The sk's sk_route_caps is set in sctp_packet_config, and later it
only needs to change when traversing the transport_list in a loop,
as the dst might be changed in the tx path.

So move sk_route_caps check and set into sctp_outq_flush_transports
from sctp_packet_transmit. This also fixes a dst leak reported by
Chen Yi:

  https://bugzilla.kernel.org/show_bug.cgi?id=212227

As calling sk_setup_caps() in sctp_packet_transmit may also set the
sk_route_caps for the ctrl sock in a netns. When the netns is being
deleted, the ctrl sock's releasing is later than dst dev's deleting,
which will cause this dev's deleting to hang and dmesg error occurs:

  unregister_netdevice: waiting for xxx to become free. Usage count = 1

Reported-by: Chen Yi <yiche@redhat.com>
Fixes: bcd623d8e9 ("sctp: call sk_setup_caps in sctp_packet_transmit instead")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
rM2-mainline
Xin Long 2021-03-19 11:52:41 +08:00 committed by David S. Miller
parent c79a707072
commit 8ff0b1f08e
2 changed files with 7 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/sctp/output.c
View File

@ -584,13 +584,6 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
goto out;
}
rcu_read_lock();
if (__sk_dst_get(sk) != tp->dst) {
dst_hold(tp->dst);
sk_setup_caps(sk, tp->dst);
}
rcu_read_unlock();
/* pack up chunks */
pkt_count = sctp_packet_pack(packet, head, gso, gfp);
if (!pkt_count) {

7
net/sctp/outqueue.c
View File

@ -1135,6 +1135,7 @@ static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
{
struct sock *sk = ctx->asoc->base.sk;
struct list_head *ltransport;
struct sctp_packet *packet;
struct sctp_transport *t;
@ -1144,6 +1145,12 @@ static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
t = list_entry(ltransport, struct sctp_transport, send_ready);
packet = &t->packet;
if (!sctp_packet_empty(packet)) {
rcu_read_lock();
if (t->dst && __sk_dst_get(sk) != t->dst) {
dst_hold(t->dst);
sk_setup_caps(sk, t->dst);
}
rcu_read_unlock();
error = sctp_packet_transmit(packet, ctx->gfp);
if (error < 0)
ctx->q->asoc->base.sk->sk_err = -error;