Re: [PATCH 58/64] powerpc: Split memset() to avoid multi-field overflow

Michael Ellerman
2021-08-05T11:37:07Z

Kees Cook <keescook@chromium.org> writes:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memset(), avoid intentionally writing across
> neighboring fields.
>
> Instead of writing across a field boundary with memset(), move the call
> to just the array, and an explicit zeroing of the prior field.
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/macintosh/smu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
> index 94fb63a7b357..59ce431da7ef 100644
> --- a/drivers/macintosh/smu.c
> +++ b/drivers/macintosh/smu.c
> @@ -848,7 +848,8 @@ int smu_queue_i2c(struct smu_i2c_cmd *cmd)
> cmd->read = cmd->info.devaddr & 0x01;
> switch(cmd->info.type) {
> case SMU_I2C_TRANSFER_SIMPLE:
> - memset(&cmd->info.sublen, 0, 4);
> + cmd->info.sublen = 0;
> + memset(&cmd->info.subaddr, 0, 3);
> break;
> case SMU_I2C_TRANSFER_COMBINED:
> cmd->info.devaddr &= 0xfe;
> --
> 2.30.2

Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>

cheers