From 4d1415811e492d9a8238f8a92dd0d51612c788e9 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Thu, 27 Jun 2019 19:48:10 -0300 Subject: [PATCH] sctp: fix error handling on stream scheduler initialization 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 --- 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 93ed07877337..25946604af85 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -153,13 +153,20 @@ 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)