Re: [PATCH] wifi: iwlegacy: Fix "field-spanning write" warning in il_enqueue_hcmd()

[Stanislaw Gruszka <stf_xl@wp.pl>]

On Thu, Sep 12, 2024 at 12:30:42PM -0500, Brandon Nielsen wrote:
> On 9/12/24 3:39 AM, Stanislaw Gruszka wrote:
> > On Thu, Sep 12, 2024 at 01:01:21AM +0200, Ben Hutchings wrote:
> > > iwlegacy uses command buffers with a payload size of 320
> > > bytes (default) or 4092 bytes (huge).  The struct il_device_cmd type
> > > describes the default buffers and there is no separate type describing
> > > the huge buffers.
> > > 
> > > The il_enqueue_hcmd() function works with both default and huge
> > > buffers, and has a memcpy() to the buffer payload.  The size of
> > > this copy may exceed 320 bytes when using a huge buffer, which
> > > now results in a run-time warning:
> > > 
> > >      memcpy: detected field-spanning write (size 1014) of single field "&out_cmd->cmd.payload" at drivers/net/wireless/intel/iwlegacy/common.c:3170 (size 320)
> > > 
> > > To fix this:
> > > 
> > > - Define a new struct type for huge buffers, with a correctly sized
> > >    payload field
> > > - When using a huge buffer in il_enqueue_hcmd(), cast the command
> > >    buffer pointer to that type when looking up the payload field
> > > 
> > > Reported-by: Martin-Éric Racine <martin-eric.racine@iki.fi>
> > > References: https://bugs.debian.org/1062421
> > > References: https://bugzilla.kernel.org/show_bug.cgi?id=219124
> > > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > > Fixes: 54d9469bc515 ("fortify: Add run-time WARN for cross-field memcpy()")
> > > Tested-by: Martin-Éric Racine <martin-eric.racine@iki.fi>
> > > Tested-by: Brandon Nielsen <nielsenb@jetfuse.net>
> > 
> > I proposed diffrent fix for this here:
> > https://lore.kernel.org/linux-wireless/20240520073210.GA693073@wp.pl/
> > but never get feedback if it works on real HW.
> > So I prefer this one, sice it was tested.
> > 
> > Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
> > 
> > Martin-Éric and Brandon, could you plase also test patch from
> > https://lore.kernel.org/linux-wireless/Zr2gxERA3RL3EwRe@elsanto/
> > if it does not break the driver?
> > 
> 
> As far as I can tell nothing breaks with that additional patch applied.

Great, thanks for testing the patch. 
Stanislaw