[PATCH stable] b43: Fix possible NULL pointer dereference in DMA code

This fixes a possible NULL pointer dereference in an error path of the DMA allocation error checking code. In case the DMA allocation address is invalid, the dev pointer is dereferenced for unmapping of the buffer. This is a cut-down version of 3ab4b64c46784ed83f213bf4e1b51d9c55858600 which is

Re: [PATCH stable] b43: Fix possible NULL pointer dereference in DMA code

On Sat, Jun 14, 2008 at 10:57:55PM +0200, Michael Buesch wrote: This fixes a possible NULL pointer dereference in an error path of the DMA allocation error checking code. In case the DMA allocation address is invalid, the dev pointer is dereferenced for unmapping of the buffer. This is a