[PATCH u-boot] regmap: fix a serious pointer casting bug

[Simon Glass]

Hi Bin,

On Tue, 16 Mar 2021 at 21:46, Bin Meng <bmeng.cn at gmail.com> wrote:
>
> Hi Simon,
>
> On Tue, Mar 16, 2021 at 2:10 PM Simon Glass <sjg at chromium.org> wrote:
> >
> > Hello Marek,
> >
> > On 03.03.21 14:15, Marek Behún wrote:
> > > There is a serious bug in regmap_read() and regmap_write() functions
> > > where an uint pointer is cast to (void *) which is then cast to (u8 *),
> > > (u16 *), (u32 *) or (u64 *), depending on register width of the map.
> > >
> > > For example given a regmap with 16-bit register width the code
> > >       int val = 0x12340000;
> > >       regmap_read(map, 0, &val);
> > > only changes the lower 16 bits of val on little-endian machines.
> > > The upper 16 bits will remain 0x1234.
> > >
> > > Nobody noticed this probably because this bug can be triggered with
> > > regmap_write() only on big-endian architectures (which are not used by
> > > many people anymore), and on little endian this bug has consequences
> > > only if register width is 8 or 16 bits and also the memory place to
> > > which regmap_read() should store it's result has non-zero upper bits,
> > > which it seems doesn't happen anywhere in U-Boot normally. CI managed to
> > > trigger this bug in unit test of dm_test_devm_regmap_field when compiled
> > > for sandbox_defconfig using LTO.
> > >
> > > Fix this simply by taking into account that regmap_raw_read() and
> > > regmap_raw_write() behave as if the data given to these functions were
> > > in little-endian format, i.e. use cpu_to_le32() / le32_to_cpu(). In
> > > regmap_read() also zero out the space so that we don't get invalid
> > > result if regmap_raw_read() does not fill the whole object.
> > >
> > > Signed-off-by: Marek Behún <marek.behun at nic.cz>
> > > ---
> > >  drivers/core/regmap.c | 13 ++++++++++++-
> > >  1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > Good catch, thanks!
> >
> > Reviewed-by: Heiko Schocher <hs at denx.de>
> >
> > bye,
> > Heiko
> > --
> > DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> > Phone: +49-8142-66989-52   Fax: +49-8142-66989-80   Email: hs at denx.de
> >
> > Applied to u-boot-dm/next, thanks!
>
> This patch is included in the LTO series.

OK, I'll drop it.

Regards,
Simon