| Message ID | 20240305105949.392092-1-giulio.benetti@benettiengineering.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mmc-utils: mmc_cmds: fix type-punned warning on &ext_csd[] casting | expand |
> 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 memcpy() the variable. If any, I would just revert commit a1b594ca735e. Thanks, Avri > > Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com> > --- > mmc_cmds.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mmc_cmds.c b/mmc_cmds.c > index ae7b876..dcd60aa 100644 > --- a/mmc_cmds.c > +++ b/mmc_cmds.c > @@ -2968,7 +2968,8 @@ do_retry: > } > > /* Test if we need to restart the download */ > - sect_done = htole32(*((__u32 > *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0])); > + memcpy(§_done, &ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0], > sizeof(__u32)); > + sect_done = htole32(sect_done); > /* 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 >
> > 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 memcpy() the variable. > If any, I would just revert commit a1b594ca735e. > > Thanks, > Avri Or, how about this untested option. Thanks, Avri index ae7b876..10f7532 100644 --- a/mmc_cmds.c +++ b/mmc_cmds.c @@ -58,6 +58,11 @@ #define WPTYPE_PWRON 2 #define WPTYPE_PERM 3 +static inline __u32 strict_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 = safe_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 = strict_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--) {
On 05/03/24 16:01, Avri Altman 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 memcpy() the variable. >> If any, I would just revert commit a1b594ca735e. >> >> Thanks, >> Avri > Or, how about this untested option. This is a good solution, just re-spin and renamed to per_byte_htole32(__u8 *). Hope it sounds good the name to you. Thank you Best regards
diff --git a/mmc_cmds.c b/mmc_cmds.c index ae7b876..dcd60aa 100644 --- a/mmc_cmds.c +++ b/mmc_cmds.c @@ -2968,7 +2968,8 @@ do_retry: } /* Test if we need to restart the download */ - sect_done = htole32(*((__u32 *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0])); + memcpy(§_done, &ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0], sizeof(__u32)); + sect_done = htole32(sect_done); /* By spec, host should re-start download from the first sector if sect_done is 0 */ if (sect_done == 0) { if (retry--) {
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 memcpy() the variable. Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com> --- mmc_cmds.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)