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

Michael Buesch
2008-06-10T14:37:45Z

On Tuesday 10 June 2008 16:34:21 Michael Buesch wrote:
> 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.
>

Ehm no wait a second...
What strange tree are you looking at?
This is a copy of the code from my local tree.

516 /* Check if a DMA mapping address is invalid. */
517 static bool b43_dma_mapping_error(struct b43_dmaring *ring,
518 dma_addr_t addr,
519 size_t buffersize, bool dma_to_device)
520 {
521 if (unlikely(dma_mapping_error(addr)))
522 return 1;

This code is perfectly fine.
This must be some merge error in some upstream tree.

--
Greetings Michael.