| From | Ben Hutchings <> | Date | Wed, 15 Feb 2017 22:41:41 +0000 | Subject | [PATCH 3.16 278/306] net: ep93xx_eth: Do not crash unloading module |
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3.16.40-rc1 review patch. If anyone has any objections, please let me know.
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From: Florian Fainelli <f.fainelli@gmail.com>
commit c823abac17926767fb50175e098f087a6ac684c3 upstream.
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 <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/net/ethernet/cirrus/ep93xx_eth.c | 4 ++++ 1 file changed, 4 insertions(+)
--- 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 e 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; @@ -492,6 +495,7 @@ static void ep93xx_free_buffers(struct e 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)
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