From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elena Reshetova Date: Fri, 20 Oct 2017 07:23:36 +0000 Subject: [PATCH 02/15] drivers, net, ethernet: convert mtk_eth.dma_refcnt from atomic_t to refcount_t Message-Id: <1508484229-19706-3-git-send-email-elena.reshetova@intel.com> List-Id: References: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> In-Reply-To: <1508484229-19706-1-git-send-email-elena.reshetova@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: davem@davemloft.net Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-rdma@vger.kernel.org, linux-hams@vger.kernel.org, linux-ppp@vger.kernel.org, ganeshgr@chelsio.com, nbd@openwrt.org, john@phrozen.org, sean.wang@mediatek.com, matthias.bgg@gmail.com, yishaih@mellanox.com, saeedm@mellanox.com, matanb@mellanox.com, tariqt@mellanox.com, leonro@mellanox.com, ajk@comnets.uni-bremen.de, paulus@samba.org, zbr@ioremap.net, peterz@infradead.org, keescook@chromium.org, Elena Reshetova 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 Reviewed-by: David Windsor Reviewed-by: Hans Liljestrand Signed-off-by: Elena Reshetova --- 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 5e81a72..54adfd9 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(ð->dma_refcnt)) { + if (!refcount_read(ð->dma_refcnt)) { int err = mtk_start_dma(eth); if (err) @@ -1827,8 +1827,10 @@ static int mtk_open(struct net_device *dev) napi_enable(ð->rx_napi); mtk_tx_irq_enable(eth, MTK_TX_DONE_INT); mtk_rx_irq_enable(eth, MTK_RX_DONE_INT); + refcount_set(ð->dma_refcnt, 1); } - atomic_inc(ð->dma_refcnt); + else + refcount_inc(ð->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(ð->dma_refcnt)) + if (!refcount_dec_and_test(ð->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 3d3c24a..a3af466 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 + #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; -- 2.7.4