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

[Stanislaw Gruszka <stf_xl@wp.pl>]

On Wed, Sep 18, 2024 at 01:45:57PM +0000, Kalle Valo wrote:
> Ben Hutchings <ben@decadent.org.uk> 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>
> > Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
> 
> Should this patch go wireless tree for v6.12? As this is a regression I think
> it should.
It's not driver regression per se, just false positive warning when built
with CONFIG_FORTIFY_SOURCE. But it should go to 6.12 IMHO as fix for
the warning.

Regards
Stanislaw