linux-kernel - [PATCH 04/11] net: calxedaxgmac: fix possible skb free before tx complete

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1377557126-10716-4-git-send-email-robherring2@gmail.com>
Date:	Mon, 26 Aug 2013 17:45:19 -0500
From:	Rob Herring <robherring2@...il.com>
To:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Andreas Herrmann <andreas.herrmann@...xeda.com>,
	Lennert Buytenhek <buytenh@...tstofly.org>,
	Rob Herring <rob.herring@...xeda.com>
Subject: [PATCH 04/11] net: calxedaxgmac: fix possible skb free before tx complete

From: Rob Herring <rob.herring@...xeda.com>

The TX completion code may have freed an skb before the entire sg list
was transmitted. The DMA unmap calls for the fragments could also get
skipped. Now set the skb pointer on every entry in the ring, not just
the head of the sg list. We then use the FS (first segment) bit in the
descriptors to determine skb head vs. fragment.

This also fixes similar bug in xgmac_free_tx_skbufs where clean-up of
a sg list that wraps at the end of the ring buffer would not get
unmapped.

Signed-off-by: Rob Herring <rob.herring@...xeda.com>
---
 drivers/net/ethernet/calxeda/xgmac.c | 55 ++++++++++++++++--------------------
 1 file changed, 24 insertions(+), 31 deletions(-)

diff --git a/drivers/net/ethernet/calxeda/xgmac.c b/drivers/net/ethernet/calxeda/xgmac.c
index df7e3e2..64854ad 100644
--- a/drivers/net/ethernet/calxeda/xgmac.c
+++ b/drivers/net/ethernet/calxeda/xgmac.c
@@ -470,6 +470,11 @@ static inline int desc_get_tx_ls(struct xgmac_dma_desc *p)
 	return le32_to_cpu(p->flags) & TXDESC_LAST_SEG;
 }
 
+static inline int desc_get_tx_fs(struct xgmac_dma_desc *p)
+{
+	return le32_to_cpu(p->flags) & TXDESC_FIRST_SEG;
+}
+
 static inline u32 desc_get_buf_addr(struct xgmac_dma_desc *p)
 {
 	return le32_to_cpu(p->buf1_addr);
@@ -796,7 +801,7 @@ static void xgmac_free_rx_skbufs(struct xgmac_priv *priv)
 
 static void xgmac_free_tx_skbufs(struct xgmac_priv *priv)
 {
-	int i, f;
+	int i;
 	struct xgmac_dma_desc *p;
 
 	if (!priv->tx_skbuff)
@@ -807,16 +812,15 @@ static void xgmac_free_tx_skbufs(struct xgmac_priv *priv)
 			continue;
 
 		p = priv->dma_tx + i;
-		dma_unmap_single(priv->device, desc_get_buf_addr(p),
-				 desc_get_buf_len(p), DMA_TO_DEVICE);
-
-		for (f = 0; f < skb_shinfo(priv->tx_skbuff[i])->nr_frags; f++) {
-			p = priv->dma_tx + i++;
+		if (desc_get_tx_fs(p))
+			dma_unmap_single(priv->device, desc_get_buf_addr(p),
+					 desc_get_buf_len(p), DMA_TO_DEVICE);
+		else
 			dma_unmap_page(priv->device, desc_get_buf_addr(p),
 				       desc_get_buf_len(p), DMA_TO_DEVICE);
-		}
 
-		dev_kfree_skb_any(priv->tx_skbuff[i]);
+		if (desc_get_tx_ls(p))
+			dev_kfree_skb_any(priv->tx_skbuff[i]);
 		priv->tx_skbuff[i] = NULL;
 	}
 }
@@ -853,8 +857,6 @@ static void xgmac_free_dma_desc_rings(struct xgmac_priv *priv)
  */
 static void xgmac_tx_complete(struct xgmac_priv *priv)
 {
-	int i;
-
 	while (dma_ring_cnt(priv->tx_head, priv->tx_tail, DMA_TX_RING_SZ)) {
 		unsigned int entry = priv->tx_tail;
 		struct sk_buff *skb = priv->tx_skbuff[entry];
@@ -864,33 +866,24 @@ static void xgmac_tx_complete(struct xgmac_priv *priv)
 		if (desc_get_owner(p))
 			break;
 
-		/* Verify tx error by looking at the last segment */
-		if (desc_get_tx_ls(p))
-			desc_get_tx_status(priv, p);
-
 		netdev_dbg(priv->dev, "tx ring: curr %d, dirty %d\n",
 			priv->tx_head, priv->tx_tail);
 
-		dma_unmap_single(priv->device, desc_get_buf_addr(p),
-				 desc_get_buf_len(p), DMA_TO_DEVICE);
-
-		priv->tx_skbuff[entry] = NULL;
-		priv->tx_tail = dma_ring_incr(entry, DMA_TX_RING_SZ);
-
-		if (!skb) {
-			continue;
-		}
-
-		for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
-			entry = priv->tx_tail = dma_ring_incr(priv->tx_tail,
-							      DMA_TX_RING_SZ);
-			p = priv->dma_tx + priv->tx_tail;
-
+		if (desc_get_tx_fs(p))
+			dma_unmap_single(priv->device, desc_get_buf_addr(p),
+					 desc_get_buf_len(p), DMA_TO_DEVICE);
+		else
 			dma_unmap_page(priv->device, desc_get_buf_addr(p),
 				       desc_get_buf_len(p), DMA_TO_DEVICE);
+
+		/* Check tx error on the last segment */
+		if (desc_get_tx_ls(p)) {
+			desc_get_tx_status(priv, p);
+			dev_kfree_skb(skb);
 		}
 
-		dev_kfree_skb(skb);
+		priv->tx_skbuff[entry] = NULL;
+		priv->tx_tail = dma_ring_incr(entry, DMA_TX_RING_SZ);
 	}
 
 	if (dma_ring_space(priv->tx_head, priv->tx_tail, DMA_TX_RING_SZ) >
@@ -1110,7 +1103,7 @@ static netdev_tx_t xgmac_xmit(struct sk_buff *skb, struct net_device *dev)
 
 		entry = dma_ring_incr(entry, DMA_TX_RING_SZ);
 		desc = priv->dma_tx + entry;
-		priv->tx_skbuff[entry] = NULL;
+		priv->tx_skbuff[entry] = skb;
 
 		desc_set_buf_addr_and_size(desc, paddr, len);
 		if (i < (nfrags - 1))
-- 
1.8.1.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/