linux-kernel - [PATCH 3.12 55/72] net: sun4i-emac: fix memory leak on bad packet

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Message-Id: <8556e3af49a4bcc5bbfd3582a20a4e4163f8b455.1448283890.git.jslaby@suse.cz>
Date:	Mon, 23 Nov 2015 14:12:16 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
	Stefan Roese <sr@...x.de>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	"David S . Miller" <davem@...emloft.net>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 55/72] net: sun4i-emac: fix memory leak on bad packet

From: Marc Zyngier <marc.zyngier@....com>

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

===============

commit 2670cc699a66c4cf268cb3e3f6dfc325ec14f224 upstream.

Upon reception of a new frame, the emac driver checks for a number
of error conditions, and flag the packet as "bad" if any of these
are present. It then allocates a skb unconditionally, but only uses
it if the packet is "good". On the error path, the skb is just forgotten,
and the system leaks memory.

The piece of junk I have on my desk seems to encounter such error
frequently enough so that the box goes OOM after a couple of days,
which makes me grumpy.

Fix this by moving the allocation on the "good_packet" path (and
convert it to netdev_alloc_skb while we're at it).

Tested on a random Allwinner A20 board.

Cc: Stefan Roese <sr@...x.de>
Cc: Maxime Ripard <maxime.ripard@...e-electrons.com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/net/ethernet/allwinner/sun4i-emac.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/allwinner/sun4i-emac.c b/drivers/net/ethernet/allwinner/sun4i-emac.c
index 81576c6c31e0..ac735537fe2e 100644
--- a/drivers/net/ethernet/allwinner/sun4i-emac.c
+++ b/drivers/net/ethernet/allwinner/sun4i-emac.c
@@ -623,8 +623,10 @@ static void emac_rx(struct net_device *dev)
 		}
 
 		/* Move data from EMAC */
-		skb = dev_alloc_skb(rxlen + 4);
-		if (good_packet && skb) {
+		if (good_packet) {
+			skb = netdev_alloc_skb(dev, rxlen + 4);
+			if (!skb)
+				continue;
 			skb_reserve(skb, 2);
 			rdptr = (u8 *) skb_put(skb, rxlen - 4);
 
-- 
2.6.3

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