netdev - [PATCH net] sctp: fix memleak on err handling of stream initialization

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Message-Id: <2a040bc8a75c67164a3d0e30726477c1a268c6d7.1576544284.git.marcelo.leitner@gmail.com>
Date:   Mon, 16 Dec 2019 22:01:16 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     netdev@...r.kernel.org
Cc:     Xin Long <lucien.xin@...il.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Neil Horman <nhorman@...driver.com>, linux-sctp@...r.kernel.org
Subject: [PATCH net] sctp: fix memleak on err handling of stream initialization

syzbot reported a memory leak when an allocation fails within
genradix_prealloc() for output streams. That's because
genradix_prealloc() leaves initialized members initialized when the
issue happens and SCTP stack will abort the current initialization but
without cleaning up such members.

The fix here is to always call genradix_free() when genradix_prealloc()
fails, for output and also input streams, as it suffers from the same
issue.

Reported-by: syzbot+772d9e36c490b18d51d1@...kaller.appspotmail.com
Fixes: 2075e50caf5e ("sctp: convert to genradix")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
---
 net/sctp/stream.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index df60b5ef24cbf5c6f628ab8ed88a6faaaa422b6d..e0b01bf912b3f3cdbc3f713bcfa50868e4802929 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -84,8 +84,10 @@ static int sctp_stream_alloc_out(struct sctp_stream *stream, __u16 outcnt,
 		return 0;
 
 	ret = genradix_prealloc(&stream->out, outcnt, gfp);
-	if (ret)
+	if (ret) {
+		genradix_free(&stream->out);
 		return ret;
+	}
 
 	stream->outcnt = outcnt;
 	return 0;
@@ -100,8 +102,10 @@ static int sctp_stream_alloc_in(struct sctp_stream *stream, __u16 incnt,
 		return 0;
 
 	ret = genradix_prealloc(&stream->in, incnt, gfp);
-	if (ret)
+	if (ret) {
+		genradix_free(&stream->in);
 		return ret;
+	}
 
 	stream->incnt = incnt;
 	return 0;
-- 
2.23.0