On Wed, Dec 15, 2021 at 03:25:13PM -0800, Kees Cook wrote:
> The find.h APIs are designed to be used only on unsigned long arguments.
> This can technically result in a over-read, but it is harmless in this
> case. Regardless, fix it to avoid the warning seen under -Warray-bounds,
> which we'd like to enable globally:
>
> In file included from ./include/linux/bitmap.h:9,
> from ./include/linux/cpumask.h:12,
> from ./arch/x86/include/asm/cpumask.h:5,
> from ./arch/x86/include/asm/msr.h:11,
> from ./arch/x86/include/asm/processor.h:22,
> from ./arch/x86/include/asm/cpufeature.h:5,
> from ./arch/x86/include/asm/thread_info.h:53,
> from ./include/linux/thread_info.h:60,
> from ./arch/x86/include/asm/preempt.h:7,
> from ./include/linux/preempt.h:78,
> from ./include/linux/spinlock.h:55,
> from ./include/linux/swait.h:7,
> from ./include/linux/completion.h:12,
> from drivers/iio/adc/stmpe-adc.c:10:
> drivers/iio/adc/stmpe-adc.c: In function 'stmpe_adc_probe':
> ./include/linux/find.h:98:23: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'u32[1]' {aka 'unsigned int[1]'} [-Warray-bounds]
> 98 | val = *addr | ~GENMASK(size - 1, offset);
> | ^~~~~
> drivers/iio/adc/stmpe-adc.c:258:13: note: while referencing 'norequest_mask'
> 258 | u32 norequest_mask = 0;
> | ^~~~~~~~~~~~~~
>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> drivers/iio/adc/stmpe-adc.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
> index fba659bfdb40..d2d405388499 100644
> --- a/drivers/iio/adc/stmpe-adc.c
> +++ b/drivers/iio/adc/stmpe-adc.c
> @@ -256,6 +256,7 @@ static int stmpe_adc_probe(struct platform_device *pdev)
> struct stmpe_adc *info;
> struct device_node *np;
> u32 norequest_mask = 0;
> + unsigned long bits;
> int irq_temp, irq_adc;
> int num_chan = 0;
> int i = 0;
> @@ -309,8 +310,8 @@ static int stmpe_adc_probe(struct platform_device *pdev)
>
> of_property_read_u32(np, "st,norequest-mask", &norequest_mask);
>
> - for_each_clear_bit(i, (unsigned long *) &norequest_mask,
> - (STMPE_ADC_LAST_NR + 1)) {
> + bits = norequest_mask;
This would not work on 64-bit BE architecture. It should use bitmap_from_arr32()
> + for_each_clear_bit(i, &bits, (STMPE_ADC_LAST_NR + 1)) {
> stmpe_adc_voltage_chan(&info->stmpe_adc_iio_channels[num_chan], i);
> num_chan++;
> }
> --
> 2.30.2
