linux-kernel - [PATCH] rtlwifi: get buffer_desc before trying to alloc new skb

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Date:	Thu, 12 Mar 2015 19:33:56 +0800
From:	Yang Bai <hamo.by@...il.com>
To:	Larry.Finger@...inger.net, chaoming_li@...lsil.com.cn,
	kvalo@...eaurora.org
Cc:	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, hamo.by@...il.com
Subject: [PATCH] rtlwifi: get buffer_desc before trying to alloc new skb

if rtlpriv->use_new_trx_flow == true and we run out of memory
to alloc a new skb, we will directly jump to no_new tag with
buffer_desc == NULL. Then we will dereference this NULL pointer
in function _rtl_pci_init_one_rxdesc.

Signed-off-by: Yang Bai <hamo.by@...il.com>
---
 drivers/net/wireless/rtlwifi/pci.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/rtlwifi/pci.c b/drivers/net/wireless/rtlwifi/pci.c
index a62170e..7fe04d1 100644
--- a/drivers/net/wireless/rtlwifi/pci.c
+++ b/drivers/net/wireless/rtlwifi/pci.c
@@ -820,17 +820,19 @@ static void _rtl_pci_rx_interrupt(struct ieee80211_hw *hw)
 		pci_unmap_single(rtlpci->pdev, *((dma_addr_t *)skb->cb),
 				 rtlpci->rxbuffersize, PCI_DMA_FROMDEVICE);
 
+		if (rtlpriv->use_new_trx_flow)
+			buffer_desc =
+			  &rtlpci->rx_ring[rxring_idx].buffer_desc
+				[rtlpci->rx_ring[rxring_idx].idx];
+
 		/* get a new skb - if fail, old one will be reused */
 		new_skb = dev_alloc_skb(rtlpci->rxbuffersize);
 		if (unlikely(!new_skb))
 			goto no_new;
-		if (rtlpriv->use_new_trx_flow) {
-			buffer_desc =
-			  &rtlpci->rx_ring[rxring_idx].buffer_desc
-				[rtlpci->rx_ring[rxring_idx].idx];
+		if (rtlpriv->use_new_trx_flow)
 			/*means rx wifi info*/
 			pdesc = (struct rtl_rx_desc *)skb->data;
-		}
+
 		memset(&rx_status , 0 , sizeof(rx_status));
 		rtlpriv->cfg->ops->query_rx_desc(hw, &stats,
 						 &rx_status, (u8 *)pdesc, skb);
-- 
2.3.1

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