From 79d0895140e937ba111e6420b4cd83ee75efa788 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 2 Jan 2018 19:44:37 -0200 Subject: [PATCH] sctp: fix error path in sctp_stream_init syzbot noticed a NULL pointer dereference panic in sctp_stream_free() which was caused by an incomplete error handling in sctp_stream_init(). By not clearing stream->outcnt, it made a for() in sctp_stream_free() think that it had elements to free, but not, leading to the panic. As suggested by Xin Long, this patch also simplifies the error path by moving it to the only if() that uses it. See-also: https://www.spinics.net/lists/netdev/msg473756.html See-also: https://www.spinics.net/lists/netdev/msg465024.html Reported-by: syzbot Fixes: f952be79cebd ("sctp: introduce struct sctp_stream_out_ext") Signed-off-by: Marcelo Ricardo Leitner Reviewed-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/stream.c | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-) diff --git a/net/sctp/stream.c b/net/sctp/stream.c index 76ea66b..524dfeb 100644 --- a/net/sctp/stream.c +++ b/net/sctp/stream.c @@ -156,9 +156,9 @@ int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt, sctp_stream_outq_migrate(stream, NULL, outcnt); sched->sched_all(stream); - i = sctp_stream_alloc_out(stream, outcnt, gfp); - if (i) - return i; + ret = sctp_stream_alloc_out(stream, outcnt, gfp); + if (ret) + goto out; stream->outcnt = outcnt; for (i = 0; i < stream->outcnt; i++) @@ -170,19 +170,17 @@ in: if (!incnt) goto out; - i = sctp_stream_alloc_in(stream, incnt, gfp); - if (i) { - ret = -ENOMEM; - goto free; + ret = sctp_stream_alloc_in(stream, incnt, gfp); + if (ret) { + sched->free(stream); + kfree(stream->out); + stream->out = NULL; + stream->outcnt = 0; + goto out; } stream->incnt = incnt; - goto out; -free: - sched->free(stream); - kfree(stream->out); - stream->out = NULL; out: return ret; } -- 2.7.4