On Tue, 5 Mar 2024 at 19:52, Giulio Benetti
<giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> When building with -Werror=strict-aliasing error is thrown:
>
> mmc_cmds.c: In function 'do_ffu':
> mmc_cmds.c:2972:2: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing]
> sect_done = htole32(*((__u32 *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0]));
> ^
> cc1: all warnings being treated as errors
>
> Let's fix type-punned breaking strict-aliasing by implementing local
> per_byte_htole32(__u8 *) and use it for the 2 present occurences of
> htole32(). Let's also change sect_done type to __u32 for consistency.
>
> Suggested-by: Avri Altman <Avri.Altman@xxxxxxx>
> Fixes: a1b594ca735e ("mmc-utils: ffu: Simplify ext_csd bytes parsing")
> Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx>
Applied to git.kernel.org/pub/scm/utils/mmc/mmc-utils.git master, thanks!
Kind regards
Uffe
> ---
> V1->V2:
> * implement local per_byte_htole32() as suggested by Avril Altman
> ---
> mmc_cmds.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/mmc_cmds.c b/mmc_cmds.c
> index ae7b876..936e0c5 100644
> --- a/mmc_cmds.c
> +++ b/mmc_cmds.c
> @@ -58,6 +58,11 @@
> #define WPTYPE_PWRON 2
> #define WPTYPE_PERM 3
>
> +static inline __u32 per_byte_htole32(__u8 *arr)
> +{
> + return arr[0] | arr[1] << 8 | arr[2] << 16 | arr[3] << 24;
> +}
> +
> int read_extcsd(int fd, __u8 *ext_csd)
> {
> int ret = 0;
> @@ -2807,7 +2812,7 @@ static void set_ffu_single_cmd(struct mmc_ioc_multi_cmd *multi_cmd,
> __u8 *ext_csd, unsigned int bytes, __u8 *buf,
> off_t offset)
> {
> - __u32 arg = htole32(*((__u32 *)&ext_csd[EXT_CSD_FFU_ARG_0]));
> + __u32 arg = per_byte_htole32(&ext_csd[EXT_CSD_FFU_ARG_0]);
>
> /* send block count */
> set_single_cmd(&multi_cmd->cmds[1], MMC_SET_BLOCK_COUNT, 0, 0,
> @@ -2827,7 +2832,7 @@ static void set_ffu_single_cmd(struct mmc_ioc_multi_cmd *multi_cmd,
> int do_ffu(int nargs, char **argv)
> {
> int dev_fd, img_fd;
> - int sect_done = 0, retry = 3, ret = -EINVAL;
> + int retry = 3, ret = -EINVAL;
> unsigned int sect_size;
> __u8 ext_csd[512];
> __u8 *buf = NULL;
> @@ -2835,6 +2840,7 @@ int do_ffu(int nargs, char **argv)
> char *device;
> struct mmc_ioc_multi_cmd *multi_cmd = NULL;
> unsigned int default_chunk = MMC_IOC_MAX_BYTES;
> + __u32 sect_done = 0;
>
> assert (nargs == 3 || nargs == 4);
>
> @@ -2968,7 +2974,7 @@ do_retry:
> }
>
> /* Test if we need to restart the download */
> - sect_done = htole32(*((__u32 *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0]));
> + sect_done = per_byte_htole32(&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0]);
> /* By spec, host should re-start download from the first sector if sect_done is 0 */
> if (sect_done == 0) {
> if (retry--) {
> --
> 2.34.1
>
>
