linux-kernel - Re: [PATCH 2/5] modpost: fix ishtp MODULE_DEVICE

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Date:   Sun, 8 Oct 2023 09:51:45 +0200
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hans de Goede <hdegoede@...hat.com>,
        Jiri Kosina <jkosina@...e.cz>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH 2/5] modpost: fix ishtp MODULE_DEVICE_TABLE built on big
 endian host

On 2023-10-08 02:04:45+0900, Masahiro Yamada wrote:
> When MODULE_DEVICE_TABLE(ishtp, ) is built on a host with a different
> endianness from the target architecture, it results in an incorrect
> MODULE_ALIAS().
> 
> For example, see a case where drivers/platform/x86/intel/ishtp_eclite.c
> is built as a module.

Nitpick:

... [as a module] for x86.

So the statements below can be interpreted correctly.

> 
> If you build it on a little endian host, you will get the correct
> MODULE_ALIAS:
> 
>     $ grep MODULE_ALIAS drivers/platform/x86/intel/ishtp_eclite.mod.c
>     MODULE_ALIAS("ishtp:{6A19CC4B-D760-4DE3-B14D-F25EBD0FBCD9}");
> 
> However, if you build it on a big endian host, you will get a wrong
> MODULE_ALIAS:
> 
>     $ grep MODULE_ALIAS drivers/platform/x86/intel/ishtp_eclite.mod.c
>     MODULE_ALIAS("ishtp:{BD0FBCD9-F25E-B14D-4DE3-D7606A19CC4B}");
> 
> This issue has been unnoticed because the x86 kernel is most likely built
> natively on an x86 host.
> 
> The guid field must not be reversed because guid_t is an array of __u8.
> 
> Fixes: fa443bc3c1e4 ("HID: intel-ish-hid: add support for MODULE_DEVICE_TABLE()")

+ Cc: stable@...r.kernel.org

> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Reviewed-by: Thomas Weißschuh <linux@...ssschuh.net>

Thanks!

> ---
> 
>  scripts/mod/file2alias.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 70bf6a2f585c..6583b36dbe69 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1401,10 +1401,10 @@ static int do_mhi_ep_entry(const char *filename, void *symval, char *alias)
>  /* Looks like: ishtp:{guid} */
>  static int do_ishtp_entry(const char *filename, void *symval, char *alias)
>  {
> -	DEF_FIELD(symval, ishtp_device_id, guid);
> +	DEF_FIELD_ADDR(symval, ishtp_device_id, guid);
>  
>  	strcpy(alias, ISHTP_MODULE_PREFIX "{");
> -	add_guid(alias, guid);
> +	add_guid(alias, *guid);
>  	strcat(alias, "}");
>  
>  	return 1;
> -- 
> 2.39.2
>