[PATCH u-boot v4 01/36] regmap: fix a serious pointer casting bug

Simon Glass sjg at chromium.org
Thu May 20 19:51:40 CEST 2021

Hi Marek,

On Thu, 20 May 2021 at 05:25, Marek Behún <marek.behun at nic.cz> 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 by utilizing an union { u8; u16; u32; u64; } and reading data
> into this union / writing data from this union.
> Signed-off-by: Marek Behún <marek.behun at nic.cz>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Heiko Schocher <hs at denx.de>
> Cc: Bin Meng <bmeng.cn at gmail.com>
> Cc: Pratyush Yadav <p.yadav at ti.com>
> ---
>  drivers/core/regmap.c | 59 +++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 57 insertions(+), 2 deletions(-)

I don't see a changelog here but this is v4. Are you using patman?


More information about the U-Boot mailing list