Re: [PATCH v2 0/3] firewire: fix minor issues

[Takashi Sakamoto <o-takashi@sakamocchi.jp>]

Hi,

On Fri, Jun 17, 2022 at 10:42:51AM +0200, Takashi Iwai wrote:
> On Thu, 16 Jun 2022 02:21:42 +0200,
> Takashi Sakamoto wrote:
> > 
> > Hi,
> > 
> > I realized that the second patch still includes a bug that shorter
> > buffer is allocated for block request than received length since the
> > computation is aligned to 4 without care of remainder.
> > 
> > Actually in the case of block request, the length is not necessarily
> > multiples of 4 and the packet payload has enough size of field with
> > padding to be aligned to 4, according to 1394 OHCI specification. In the
> > implementation of firewire-core driver, the field is copied without
> > the padding.
> > 
> > Please abandon them. I'm sorry to trouble you.
> 
> So this implies that the type declaration of data[] rather looks
> wrong?

Your great insight.

Indeed, I can not find any code to dereference the array for u32
element. In all of cases, the 'struct fw_request.data' is passed losing
its pointer type (void *), then copied by the length in byte count. At
least, I can not find any warning or error at compiling the driver after
replacing the 'u32 []' with 'u8 []'.

Even if it were dereferenced, accessing over allocation boundary hardly
occurred since typical implementation of slab allocator maintains various
sizes of memory objects but multiples of 4.

It's possible to declare it with byte array, I think.


Thanks

Takashi Sakamoto