Re: BUG: NULL pointer dereference at 00000000 -- IP: [<f8e783d5>] :b43:b43_dma_mapping_error+0x16/0x155

[Michael Buesch]

On Tuesday 10 June 2008 16:29:17 Vegard Nossum wrote:
> On Tue, Jun 10, 2008 at 4:23 PM, Michael Buesch <mb@xxxxxxxxx> wrote:
> > On Tuesday 10 June 2008 16:09:37 Miles Lane wrote:
> >> BUG: unable to handle kernel NULL pointer dereference at 00000000
> >> IP: [<f8e783d5>] :b43:b43_dma_mapping_error+0x16/0x155
> >
> >
> > It seems to crash at
> >  60 extern const struct dma_mapping_ops *dma_ops;
> >  61
> >  62 static inline int dma_mapping_error(dma_addr_t dma_addr)
> >  63 {
> >  64         if (dma_ops->mapping_error)
> >  65                 return dma_ops->mapping_error(dma_addr);
> >  66
> >  67         return (dma_addr == bad_dma_address);
> >  68 }
> 
> No, this is wrong.
> 
> /* Check if a DMA mapping address is invalid. */
> static bool b43_dma_mapping_error(struct b43_dmaring *ring,
>                                   dma_addr_t addr,
>                                   size_t buffersize, bool dma_to_device)
> {
>         if (unlikely(dma_mapping_error(ring->dev->dev->dma_dev, addr)))
> 
> It crashes on this line ---^

Which calls dma_mapping_error(), correct?

But you are right. I see the bug now.
ring->dev is assigned after the call.
I wonder why it works reliably on all of my machines.

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