From c823abac17926767fb50175e098f087a6ac684c3 Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Sun, 4 Dec 2016 19:22:05 -0800 Subject: [PATCH] net: ep93xx_eth: Do not crash unloading module When we unload the ep93xx_eth, whether we have opened the network interface or not, we will either hit a kernel paging request error, or a simple NULL pointer de-reference because: - if ep93xx_open has been called, we have created a valid DMA mapping for ep->descs, when we call ep93xx_stop, we also call ep93xx_free_buffers, ep->descs now has a stale value - if ep93xx_open has not been called, we have a NULL pointer for ep->descs, so performing any operation against that address just won't work Fix this by adding a NULL pointer check for ep->descs which means that ep93xx_free_buffers() was able to successfully tear down the descriptors and free the DMA cookie as well. Fixes: 1d22e05df818 ("[PATCH] Cirrus Logic ep93xx ethernet driver") Signed-off-by: Florian Fainelli Signed-off-by: David S. Miller --- drivers/net/ethernet/cirrus/ep93xx_eth.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/ethernet/cirrus/ep93xx_eth.c b/drivers/net/ethernet/cirrus/ep93xx_eth.c index de9f7c97d916..9a161e981529 100644 --- a/drivers/net/ethernet/cirrus/ep93xx_eth.c +++ b/drivers/net/ethernet/cirrus/ep93xx_eth.c @@ -468,6 +468,9 @@ static void ep93xx_free_buffers(struct ep93xx_priv *ep) struct device *dev = ep->dev->dev.parent; int i; + if (!ep->descs) + return; + for (i = 0; i < RX_QUEUE_ENTRIES; i++) { dma_addr_t d; @@ -490,6 +493,7 @@ static void ep93xx_free_buffers(struct ep93xx_priv *ep) dma_free_coherent(dev, sizeof(struct ep93xx_descs), ep->descs, ep->descs_dma_addr); + ep->descs = NULL; } static int ep93xx_alloc_buffers(struct ep93xx_priv *ep) -- 2.30.2