Re: [PATCH 03/44 take 2] [UBI] user-space API header

Arnd Bergmann
2007-02-20T13:18:13Z

On Tuesday 20 February 2007 14:07, Artem Bityutskiy wrote:
>
> > This structure is not suitable for an ioctl call, because it has
> > incompatible layout between 32 and 64 bit processes. The easiest
> > fix for this would be to change the 'name' field to an array
> > instead of a pointer.
>
> Will be fixed thanks. Just out of curiosity, could you please provide an
> example when this may be a problem.

On a 64 bit process with a 32 bit user app calling this ioctl, the kernel
would read the pointer value from the 8 bytes at the end, which means that
it will read four bytes after the end of the structure and interpret
whatever it finds as a pointer, instead of using only the first four
bytes as the lower half.