[PATCH 4.20 17/52] sctp: remove sched init from sctp_stream_init

From: Greg Kroah-Hartman
Date: Mon Mar 18 2019 - 05:29:12 EST

4.20-stable review patch. If anyone has any objections, please let me know.


From: Xin Long <lucien.xin@xxxxxxxxx>

[ Upstream commit 2e990dfd13974d9eae493006f42ffb48707970ef ]

syzbot reported a NULL-ptr deref caused by that sched->init() in
sctp_stream_init() set stream->rr_next = NULL.

kasan: GPF could be caused by NULL-ptr deref or user memory access
RIP: 0010:sctp_sched_rr_dequeue+0xd3/0x170 net/sctp/stream_sched_rr.c:141
Call Trace:
sctp_outq_dequeue_data net/sctp/outqueue.c:90 [inline]
sctp_outq_flush_data net/sctp/outqueue.c:1079 [inline]
sctp_outq_flush+0xba2/0x2790 net/sctp/outqueue.c:1205

All sched info is saved in sout->ext now, in sctp_stream_init()
sctp_stream_alloc_out() will not change it, there's no need to
call sched->init() again, since sctp_outq_init() has already
done it.

Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations")
Reported-by: syzbot+4c9934f20522c0efd657@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
net/sctp/stream.c | 2 --
1 file changed, 2 deletions(-)

--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -230,8 +230,6 @@ int sctp_stream_init(struct sctp_stream
for (i = 0; i < stream->outcnt; i++)
SCTP_SO(stream, i)->state = SCTP_STREAM_OPEN;

- sched->init(stream);
if (!incnt)