From: Sergei Shtylyov Date: Mon, 7 Mar 2016 22:36:28 +0000 (+0300) Subject: sh_eth: fix NULL pointer dereference in sh_eth_ring_format() X-Git-Tag: v4.6-rc1~91^2~97^2~1 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=c1b7fca65070bfadca94dd53a4e6b71cd4f69715;p=linux-2.6-block.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 Signed-off-by: Sergei Shtylyov Signed-off-by: David S. Miller --- 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);