On 2/14/26 2:39 PM, Krzysztof Kozlowski wrote:
> Use __counted_by_ptr() attribute on the acpm_xfer buffers so UBSAN will
> validate runtime that we do not pass over the buffer size, thus making
> code safer.
>
> Usage of __counted_by_ptr() (or actually __counted_by()) requires that
> counter is initialized before counted array.
>
> Signed-off-by: Krzysztof Kozlowski <[email protected]>
>
> ---
>
> __counted_by_ptr() actually maps to __counted_by() for clang v20.
> Alternatively we could introduce new __sized_by(), already supported by
> clang v20, but it is not available for GCC, AFAIU.
>
> RFT, testing would need clang=20+ with COMNFIG_UBSAN and
> CONFIG_UBSAN_BOUNDS enabled.
Tested cpufreq (ACPM DVFS) with:
CONFIG_CLANG_VERSION=220100
CONFIG_UBSAN=y
CONFIG_UBSAN_BOUNDS=y
Tested-by: Tudor Ambarus <[email protected]>
Reviewed-by: Tudor Ambarus <[email protected]>
> ---
> drivers/firmware/samsung/exynos-acpm-dvfs.c | 4 ++--
> drivers/firmware/samsung/exynos-acpm.h | 4 ++--
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/samsung/exynos-acpm-dvfs.c
> b/drivers/firmware/samsung/exynos-acpm-dvfs.c
> index 55ec6ad9d87e..a4864973f65d 100644
> --- a/drivers/firmware/samsung/exynos-acpm-dvfs.c
> +++ b/drivers/firmware/samsung/exynos-acpm-dvfs.c
> @@ -24,12 +24,12 @@ static void acpm_dvfs_set_xfer(struct acpm_xfer *xfer,
> u32 *cmd, size_t cmdlen,
> unsigned int acpm_chan_id, bool response)
> {
> xfer->acpm_chan_id = acpm_chan_id;
> - xfer->txd = cmd;
> xfer->txcnt = cmdlen;
> + xfer->txd = cmd;
>
> if (response) {
> - xfer->rxd = cmd;
> xfer->rxcnt = cmdlen;
> + xfer->rxd = cmd;
> }
> }
>
> diff --git a/drivers/firmware/samsung/exynos-acpm.h
> b/drivers/firmware/samsung/exynos-acpm.h
> index 422fbcac7284..8392fcb91f45 100644
> --- a/drivers/firmware/samsung/exynos-acpm.h
> +++ b/drivers/firmware/samsung/exynos-acpm.h
> @@ -8,8 +8,8 @@
> #define __EXYNOS_ACPM_H__
>
> struct acpm_xfer {
> - const u32 *txd;
> - u32 *rxd;
> + const u32 *txd __counted_by_ptr(txcnt);
> + u32 *rxd __counted_by_ptr(rxcnt);
> size_t txcnt;
> size_t rxcnt;
> unsigned int acpm_chan_id;
>
