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

Michael Buesch
2008-06-10T14:34:55Z

On Tuesday 10 June 2008 16:29:17 Vegard Nossum wrote:
> On Tue, Jun 10, 2008 at 4:23 PM, Michael Buesch <mb@bu3sch.de> 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.