linux-kernel - [PATCH 4.14 134/159] sctp: silence warns on sctp_stream

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Date:   Fri, 22 Dec 2017 09:46:59 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xin Long <lucien.xin@...il.com>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.14 134/159] sctp: silence warns on sctp_stream_init allocations

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

------------------

From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>


[ Upstream commit 1ae2eaaa229bc350b6f38fbf4ab9c873532aecfb ]

As SCTP supports up to 65535 streams, that can lead to very large
allocations in sctp_stream_init(). As Xin Long noticed, systems with
small amounts of memory are more prone to not have enough memory and
dump warnings on dmesg initiated by user actions. Thus, silence them.

Also, if the reallocation of stream->out is not necessary, skip it and
keep the memory we already have.

Reported-by: Xin Long <lucien.xin@...il.com>
Tested-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/sctp/stream.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -40,9 +40,14 @@ int sctp_stream_init(struct sctp_stream
 {
 	int i;
 
+	gfp |= __GFP_NOWARN;
+
 	/* Initial stream->out size may be very big, so free it and alloc
-	 * a new one with new outcnt to save memory.
+	 * a new one with new outcnt to save memory if needed.
 	 */
+	if (outcnt == stream->outcnt)
+		goto in;
+
 	kfree(stream->out);
 
 	stream->out = kcalloc(outcnt, sizeof(*stream->out), gfp);
@@ -53,6 +58,7 @@ int sctp_stream_init(struct sctp_stream
 	for (i = 0; i < stream->outcnt; i++)
 		stream->out[i].state = SCTP_STREAM_OPEN;
 
+in:
 	if (!incnt)
 		return 0;