From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date: Mon, 7 Mar 2016 22:36:28 +0000 (+0300)
Subject: sh_eth: fix NULL pointer dereference in sh_eth_ring_format()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c1b7fca65070bfadca94dd53a4e6b71cd4f69715;p=openwrt%2Fstaging%2Fblogic.git

sh_eth: fix NULL pointer dereference in sh_eth_ring_format()

In a low memory situation, if netdev_alloc_skb() fails on a first RX ring
loop iteration  in sh_eth_ring_format(), 'rxdesc' is still NULL.  Avoid
kernel oops by adding the 'rxdesc' check after the loop.

Reported-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 9c6448915b65..6fb75a1d68b9 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1154,7 +1154,8 @@ static void sh_eth_ring_format(struct net_device *ndev)
 	mdp->dirty_rx = (u32) (i - mdp->num_rx_ring);
 
 	/* Mark the last entry as wrapping the ring. */
-	rxdesc->status |= cpu_to_le32(RD_RDLE);
+	if (rxdesc)
+		rxdesc->status |= cpu_to_le32(RD_RDLE);
 
 	memset(mdp->tx_ring, 0, tx_ringsize);