From 2a8e1d0c9646f78fdd0f00e2eadf8210bbf810a7 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Thu, 27 Jun 2019 19:48:10 -0300 Subject: sctp: fix error handling on stream scheduler initialization [ Upstream commit 4d1415811e492d9a8238f8a92dd0d51612c788e9 ] It allocates the extended area for outbound streams only on sendmsg calls, if they are not yet allocated. When using the priority stream scheduler, this initialization may imply into a subsequent allocation, which may fail. In this case, it was aborting the stream scheduler initialization but leaving the ->ext pointer (allocated) in there, thus in a partially initialized state. On a subsequent call to sendmsg, it would notice the ->ext pointer in there, and trip on uninitialized stuff when trying to schedule the data chunk. The fix is undo the ->ext initialization if the stream scheduler initialization fails and avoid the partially initialized state. Although syzkaller bisected this to commit 4ff40b86262b ("sctp: set chunk transport correctly when it's a new asoc"), this bug was actually introduced on the commit I marked below. Reported-by: syzbot+c1a380d42b190ad1e559@syzkaller.appspotmail.com Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") Tested-by: Xin Long Signed-off-by: Marcelo Ricardo Leitner Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/stream.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/net/sctp/stream.c b/net/sctp/stream.c index b6bb68adac6e..f72dfda4025d 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -168,13 +168,20 @@ out: int sctp_stream_init_ext(struct sctp_stream *stream, __u16 sid) { struct sctp_stream_out_ext *soute; + int ret; soute = kzalloc(sizeof(*soute), GFP_KERNEL); if (!soute) return -ENOMEM; SCTP_SO(stream, sid)->ext = soute; - return sctp_sched_init_sid(stream, sid, GFP_KERNEL); + ret = sctp_sched_init_sid(stream, sid, GFP_KERNEL); + if (ret) { + kfree(SCTP_SO(stream, sid)->ext); + SCTP_SO(stream, sid)->ext = NULL; + } + + return ret; } void sctp_stream_free(struct sctp_stream *stream) -- cgit v1.2.3