From: Ulf Hansson <ulf.hansson@linaro.org>
To: Giulio Benetti <giulio.benetti@benettiengineering.com>
Cc: Avri Altman <Avri.Altman@wdc.com>, linux-mmc@vger.kernel.org
Subject: Re: [PATCH v2] mmc-utils: mmc_cmds: fix type-punned warning on &ext_csd[] casting
Date: Thu, 7 Mar 2024 12:02:31 +0100 [thread overview]
Message-ID: <CAPDyKFrBEK8nKM0ELYQDiE-A1BLG01qZxpuq3PvKMUD+h9NuEA@mail.gmail.com> (raw)
In-Reply-To: <20240305184513.400364-1-giulio.benetti@benettiengineering.com>
On Tue, 5 Mar 2024 at 19:52, Giulio Benetti
<giulio.benetti@benettiengineering.com> 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@wdc.com>
> Fixes: a1b594ca735e ("mmc-utils: ffu: Simplify ext_csd bytes parsing")
> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
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
>
>
next prev parent reply other threads:[~2024-03-07 11:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 10:59 [PATCH] mmc-utils: mmc_cmds: fix type-punned warning on &ext_csd[] casting Giulio Benetti
2024-03-05 14:52 ` Avri Altman
2024-03-05 15:01 ` Avri Altman
2024-03-05 18:45 ` [PATCH v2] " Giulio Benetti
2024-03-05 19:48 ` Avri Altman
2024-03-07 11:02 ` Ulf Hansson [this message]
2024-03-05 18:46 ` [PATCH] " Giulio Benetti
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