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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 10:23:36 +0300
committerDavid S. Miller <davem@davemloft.net>2017-10-22 04:22:38 +0300
commitc6d4e63e065e796d2f2734c1e4e13f85f1c1c5e4 (patch)
tree378dcc65e175a716d39e1ca417fcc2906b862233 /drivers/net/ethernet/mediatek
parenteaf6ab76430881c30695a9195ce37d6b11b04997 (diff)
downloadlinux-c6d4e63e065e796d2f2734c1e4e13f85f1c1c5e4.tar.xz
drivers, net, ethernet: convert mtk_eth.dma_refcnt from atomic_t to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable mtk_eth.dma_refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet/mediatek')
-rw-r--r--drivers/net/ethernet/mediatek/mtk_eth_soc.c8
-rw-r--r--drivers/net/ethernet/mediatek/mtk_eth_soc.h4
2 files changed, 8 insertions, 4 deletions
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 5e81a7263654..54adfd967858 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1817,7 +1817,7 @@ static int mtk_open(struct net_device *dev)
struct mtk_eth *eth = mac->hw;
/* we run 2 netdevs on the same dma ring so we only bring it up once */
- if (!atomic_read(&eth->dma_refcnt)) {
+ if (!refcount_read(&eth->dma_refcnt)) {
int err = mtk_start_dma(eth);
if (err)
@@ -1827,8 +1827,10 @@ static int mtk_open(struct net_device *dev)
napi_enable(&eth->rx_napi);
mtk_tx_irq_enable(eth, MTK_TX_DONE_INT);
mtk_rx_irq_enable(eth, MTK_RX_DONE_INT);
+ refcount_set(&eth->dma_refcnt, 1);
}
- atomic_inc(&eth->dma_refcnt);
+ else
+ refcount_inc(&eth->dma_refcnt);
phy_start(dev->phydev);
netif_start_queue(dev);
@@ -1868,7 +1870,7 @@ static int mtk_stop(struct net_device *dev)
phy_stop(dev->phydev);
/* only shutdown DMA if this is the last user */
- if (!atomic_dec_and_test(&eth->dma_refcnt))
+ if (!refcount_dec_and_test(&eth->dma_refcnt))
return 0;
mtk_tx_irq_disable(eth, MTK_TX_DONE_INT);
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index 3d3c24a28112..a3af4660de81 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -15,6 +15,8 @@
#ifndef MTK_ETH_H
#define MTK_ETH_H
+#include <linux/refcount.h>
+
#define MTK_QDMA_PAGE_SIZE 2048
#define MTK_MAX_RX_LENGTH 1536
#define MTK_TX_DMA_BUF_LEN 0x3fff
@@ -632,7 +634,7 @@ struct mtk_eth {
struct regmap *pctl;
u32 chip_id;
bool hwlro;
- atomic_t dma_refcnt;
+ refcount_t dma_refcnt;
struct mtk_tx_ring tx_ring;
struct mtk_rx_ring rx_ring[MTK_MAX_RX_RING_NUM];
struct mtk_rx_ring rx_ring_qdma;