Skip to contentSkip to conversation

net: sxgbe: Fix waring for double kfree()

PATCH Applied Kukjin Kim 3 participants 6 messages Jan 15, 2015 – Feb 6, 2015

Subsystems (4)
Networking Network drivers Kernel janitors Samsung sxgbe drivers
lore
Share & tools
lore

Kukjin Kim

author
#0 lore raw

PATCH 1/1 net: sxgbe: Fix waring for double kfree()

From: Byungho An <[email protected]>

This patch fixes double kfree() calls at init_rx_ring() because it causes static checker warning.

Reported-by Dan Carpenter <[email protected]>
Signed-off-by Byungho An <[email protected]>
Signed-off-by Kukjin Kim <[email protected]>
---
 drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)
drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c +10 -11
index 6984944..fe7538d 100644
@@ -474,13 +474,19 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 	/* allocate memory for RX skbuff array */
 	rx_ring->rx_skbuff_dma = kmalloc_array(rx_rsize,
 					       sizeof(dma_addr_t), GFP_KERNEL);
-	if (rx_ring->rx_skbuff_dma == NULL)
-		goto dmamem_err;
+	if (!rx_ring->rx_skbuff_dma) {
+		dma_free_coherent(priv->device,
+				  rx_rsize * sizeof(struct sxgbe_rx_norm_desc),
+				  rx_ring->dma_rx, rx_ring->dma_rx_phy);
+		goto error;
+	}
 
 	rx_ring->rx_skbuff = kmalloc_array(rx_rsize,
 					   sizeof(struct sk_buff *), GFP_KERNEL);
-	if (rx_ring->rx_skbuff == NULL)
-		goto rxbuff_err;
+	if (!rx_ring->rx_skbuff) {
+		kfree(rx_ring->rx_skbuff_dma);
+		goto error;
+	}
 
 	/* initialise the buffers */
 	for (desc_index = 0; desc_index < rx_rsize; desc_index++) {

@@ -502,13 +508,6 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 err_init_rx_buffers:
 	while (--desc_index >= 0)
 		free_rx_ring(priv->device, rx_ring, desc_index);
-	kfree(rx_ring->rx_skbuff);
-rxbuff_err:
-	kfree(rx_ring->rx_skbuff_dma);
-dmamem_err:
-	dma_free_coherent(priv->device,
-			  rx_rsize * sizeof(struct sxgbe_rx_norm_desc),
-			  rx_ring->dma_rx, rx_ring->dma_rx_phy);
 error:
 	return -ENOMEM;
 }
Signature · 1 line
2.0.0
#1 lore raw

drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c static int init_rx_ring(struct net_device *dev, u8 queue_no, · line 486

Quoted 5 lines · Kukjin Kim
drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c +1 -2
 	rx_ring->rx_skbuff = kmalloc_array(rx_rsize,
 					   sizeof(struct sk_buff *), GFP_KERNEL);
-	if (rx_ring->rx_skbuff == NULL)
-		goto rxbuff_err;
+	if (!rx_ring->rx_skbuff) {

This is missing a dma_free_coherent() here.

drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c static int init_rx_ring(struct net_device *dev, u8 queue_no, · line 505

Quoted 11 lines
drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c +3 -1
+		kfree(rx_ring->rx_skbuff_dma);
+		goto error;
+	}
 
 	/* initialise the buffers */
 	for (desc_index = 0; desc_index < rx_rsize; desc_index++) {

@@ -502,13 +508,6 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 err_init_rx_buffers:
 	while (--desc_index >= 0)
 		free_rx_ring(priv->device, rx_ring, desc_index);
-	kfree(rx_ring->rx_skbuff);

The double free bug is that free_rx_ring() frees kfree(rx_ring->rx_skbuff_dma); and kfree(rx_ring->rx_skbuff); so just calling it in a loop here will cause a double free.

Also free_rx_ring() doesn't take an index parameter, it takes a size parameter.

The right way to fix this is to create a release function that mirrors sxgbe_init_rx_buffers().

static void sxgbe_free_rx_buffers(struct net_device *dev,
struct sxgbe_rx_norm_desc *p, int i, unsigned int dma_buf_sz, struct sxgbe_rx_queue *rx_ring)

{
        struct sxgbe_priv_data *priv = netdev_priv(dev);

        kfree_skb(rx_ring->rx_skbuff[i]);
        dma_unmap_single(priv->device, rx_ring->rx_skbuff_dma[i],
                         dma_buf_sz, DMA_FROM_DEVICE);
}

Then just swap that into the free loop instead of the free_rx_ring().

err_init_rx_buffers:

	while (--desc_index >= 0) {
		struct sxgbe_rx_norm_desc *p;

		p = rx_ring->dma_rx + desc_index;
		sxgbe_init_rx_buffers(dev, p, desc_index, bfsize, rx_ring);
	}
	kfree(rx_ring->rx_skbuff);

Something like that.

regards,
dan carpenter

#3 lore raw
Quoted 5 lines · David Miller

From: Kukjin Kim <[email protected]>
Date: Thu, 15 Jan 2015 10:43:11 +0900

Quoted 2 lines

From: Byungho An <[email protected]>

Quoted 8 lines
Quoted 6 lines

This patch fixes double kfree() calls at init_rx_ring() because it causes static checker warning.

Reported-by Dan Carpenter <[email protected]>
Signed-off-by Byungho An <[email protected]>
Signed-off-by Kukjin Kim <[email protected]>

Applied.

It does silence the warning but it doesn't fix the bug.

Kukjin, let me know if you have any questions. I can write the fix if you need me to.

regards,
dan carpenter

#4 lore raw

PATCH 1/1 net: sxgbe: fix error handling in init_rx_ring()

There are a couple bugs with the error handling in this function.

1) If we can't allocate "rx_ring->rx_skbuff" then we should call dma_free_coherent() but we don't.
2) free_rx_ring() frees "rx_ring->rx_skbuff_dma" and "rx_ring->rx_skbuff" so calling it in a loop causes a double free.

Also it was a bit confusing how we sometimes freed things before doing the goto. I've cleaned it up so it does error handling in normal kernel style.

Signed-off-by Dan Carpenter <[email protected]>
drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c +43 -14
index 11288d4..c8a01ee 100644
@@ -364,6 +364,26 @@ static int sxgbe_init_rx_buffers(struct net_device *dev,
 
 	return 0;
 }
+
+/**
+ * sxgbe_free_rx_buffers - free what sxgbe_init_rx_buffers() allocated
+ * @dev: net device structure
+ * @rx_ring: ring to be freed
+ * @rx_rsize: ring size
+ * Description:  this function initializes the DMA RX descriptor
+ */
+static void sxgbe_free_rx_buffers(struct net_device *dev,
+				  struct sxgbe_rx_norm_desc *p, int i,
+				  unsigned int dma_buf_sz,
+				  struct sxgbe_rx_queue *rx_ring)
+{
+	struct sxgbe_priv_data *priv = netdev_priv(dev);
+
+	kfree_skb(rx_ring->rx_skbuff[i]);
+	dma_unmap_single(priv->device, rx_ring->rx_skbuff_dma[i],
+			 dma_buf_sz, DMA_FROM_DEVICE);
+}
+
 /**
  * init_tx_ring - init the TX descriptor ring
  * @dev: net device structure

@@ -456,7 +476,7 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 	/* RX ring is not allcoated */
 	if (rx_ring = NULL) {
 		netdev_err(dev, "No memory for RX queue\n");
-		goto error;
+		return -ENOMEM;
 	}
 
 	/* assign queue number */

@@ -468,23 +488,21 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 					      &rx_ring->dma_rx_phy, GFP_KERNEL);
 
 	if (rx_ring->dma_rx = NULL)
-		goto error;
+		return -ENOMEM;
 
 	/* allocate memory for RX skbuff array */
 	rx_ring->rx_skbuff_dma = kmalloc_array(rx_rsize,
 					       sizeof(dma_addr_t), GFP_KERNEL);
 	if (!rx_ring->rx_skbuff_dma) {
-		dma_free_coherent(priv->device,
-				  rx_rsize * sizeof(struct sxgbe_rx_norm_desc),
-				  rx_ring->dma_rx, rx_ring->dma_rx_phy);
-		goto error;
+		ret = -ENOMEM;
+		goto err_free_dma_rx;
 	}
 
 	rx_ring->rx_skbuff = kmalloc_array(rx_rsize,
 					   sizeof(struct sk_buff *), GFP_KERNEL);
 	if (!rx_ring->rx_skbuff) {
-		kfree(rx_ring->rx_skbuff_dma);
-		goto error;
+		ret = -ENOMEM;
+		goto err_free_skbuff_dma;
 	}
 
 	/* initialise the buffers */

@@ -494,7 +512,7 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 		ret = sxgbe_init_rx_buffers(dev, p, desc_index,
 					    bfsize, rx_ring);
 		if (ret)
-			goto err_init_rx_buffers;
+			goto err_free_rx_buffers;
 	}
 
 	/* initalise counters */

@@ -504,11 +522,22 @@ static int init_rx_ring(struct net_device *dev, u8 queue_no,
 
 	return 0;
 
-err_init_rx_buffers:
-	while (--desc_index >= 0)
-		free_rx_ring(priv->device, rx_ring, desc_index);
-error:
-	return -ENOMEM;
+err_free_rx_buffers:
+	while (--desc_index >= 0) {
+		struct sxgbe_rx_norm_desc *p;
+
+		p = rx_ring->dma_rx + desc_index;
+		sxgbe_free_rx_buffers(dev, p, desc_index, bfsize, rx_ring);
+	}
+	kfree(rx_ring->rx_skbuff);
+err_free_skbuff_dma:
+	kfree(rx_ring->rx_skbuff_dma);
+err_free_dma_rx:
+	dma_free_coherent(priv->device,
+			  rx_rsize * sizeof(struct sxgbe_rx_norm_desc),
+			  rx_ring->dma_rx, rx_ring->dma_rx_phy);
+
+	return ret;
 }
 /**
  * free_tx_ring - free the TX descriptor ring
maintainer
#5 lore raw

Re: [patch] net: sxgbe: fix error handling in init_rx_ring()

From: Dan Carpenter <[email protected]>
Date: Thu, 5 Feb 2015 11:00:42 +0300

Quoted 7 lines

There are a couple bugs with the error handling in this function.

1) If we can't allocate "rx_ring->rx_skbuff" then we should call dma_free_coherent() but we don't.
2) free_rx_ring() frees "rx_ring->rx_skbuff_dma" and "rx_ring->rx_skbuff" so calling it in a loop causes a double free.

Quoted 5 lines

Also it was a bit confusing how we sometimes freed things before doing the goto. I've cleaned it up so it does error handling in normal kernel style.

Signed-off-by Dan Carpenter <[email protected]>

Looks good, applied, thanks Dan.