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Subject[PATCH 02/16] drivers, net, ethernet: convert mtk_eth.dma_refcnt from atomic_t to refcount_t
Date
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
---
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 8 +++++---
drivers/net/ethernet/mediatek/mtk_eth_soc.h | 4 +++-
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 bf6317e..d27f9d9 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1725,7 +1725,7 @@ 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)
@@ -1735,8 +1735,10 @@ static int mtk_open(struct net_device *dev)
napi_enable(&eth->rx_napi);
mtk_irq_enable(eth, MTK_QDMA_INT_MASK, MTK_TX_DONE_INT);
mtk_irq_enable(eth, MTK_PDMA_INT_MASK, 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);
@@ -1776,7 +1778,7 @@ 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_irq_disable(eth, MTK_QDMA_INT_MASK, 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 99b1c8e..e5b99b7 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
@@ -541,7 +543,7 @@ 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 napi_struct tx_napi;
--
2.7.4
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