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* [PATCH][RESEND] Avoid possible NULL pointer deref in 3c359 driver
@ 2007-08-04 18:31 Jesper Juhl
  0 siblings, 0 replies; only message in thread
From: Jesper Juhl @ 2007-08-04 18:31 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Linux Kernel Mailing List, Mike Phillips, netdev, linux-tr,
	Jesper Juhl, davem

(Resending old patch originally submitted at 1/7-2007 02:19)

In xl_freemem(), if dev_if is NULL, the line 
   struct xl_private *xl_priv =(struct xl_private *)dev->priv;
will cause a NULL pointer dereference. However, if we move 
that assignment below the 'if' statement that tests for a NULL 
'dev', then that NULL deref can never happen.
It never hurts to be safe :-)

Signed-off-by: Jesper Juhl <>

diff --git a/drivers/net/tokenring/3c359.c b/drivers/net/tokenring/3c359.c
index e22a3f5..671f4da 100644
--- a/drivers/net/tokenring/3c359.c
+++ b/drivers/net/tokenring/3c359.c
@@ -1044,15 +1044,17 @@ static void xl_freemem(struct net_device *dev)
 static irqreturn_t xl_interrupt(int irq, void *dev_id) 
 	struct net_device *dev = (struct net_device *)dev_id;
- 	struct xl_private *xl_priv =(struct xl_private *)dev->priv;
-	u8 __iomem * xl_mmio = xl_priv->xl_mmio ; 
-	u16 intstatus, macstatus  ;
+ 	struct xl_private *xl_priv;
+	u8 __iomem * xl_mmio; 
+	u16 intstatus, macstatus;
 	if (!dev) { 
-		printk(KERN_WARNING "Device structure dead, aaahhhh !\n") ;
+		printk(KERN_WARNING "3c359: Device structure dead, aaahhhh!\n");
 		return IRQ_NONE; 
+	xl_priv = (struct xl_private *)dev->priv;
+	xl_mmio = xl_priv->xl_mmio;
 	intstatus = readw(xl_mmio + MMIO_INTSTATUS) ;  
 	if (!(intstatus & 1)) /* We didn't generate the interrupt */

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2007-08-04 18:31 [PATCH][RESEND] Avoid possible NULL pointer deref in 3c359 driver Jesper Juhl

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