From: Jesper Juhl 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. Signed-off-by: Jesper Juhl Signed-off-by: Andrew Morton --- drivers/net/tokenring/3c359.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff -puN drivers/net/tokenring/3c359.c~avoid-possible-null-pointer-deref-in-3c359-driver drivers/net/tokenring/3c359.c --- a/drivers/net/tokenring/3c359.c~avoid-possible-null-pointer-deref-in-3c359-driver +++ a/drivers/net/tokenring/3c359.c @@ -1042,15 +1042,17 @@ static void xl_freemem(struct net_device static irqreturn_t xl_interrupt(int irq, void *dev_id) { struct net_device *dev = (struct net_device *)dev_id; - struct xl_private *xl_priv =netdev_priv(dev); - 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 = netdev_priv(dev); + xl_mmio = xl_priv->xl_mmio; intstatus = readw(xl_mmio + MMIO_INTSTATUS) ; if (!(intstatus & 1)) /* We didn't generate the interrupt */ _