linux-kernel - Re: [PATCH] uapi: bitops: use UAPI-safe variant of BITS_PER

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aGKkw6b1QPTf9yii@yury>
Date: Mon, 30 Jun 2025 10:52:51 -0400
From: Yury Norov <yury.norov@...il.com>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>,
	Vincent Mailhol <mailhol.vincent@...adoo.fr>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uapi: bitops: use UAPI-safe variant of BITS_PER_LONG
 again (2)

On Mon, Jun 30, 2025 at 03:02:18PM +0200, Thomas Weißschuh wrote:
> BITS_PER_LONG does not exist in UAPI headers, so can't be used by the UAPI
> __GENMASK(). Instead __BITS_PER_LONG needs to be used.
> 
> When __GENMASK() was introduced in commit 3c7a8e190bc5 ("uapi: introduce uapi-friendly macros for GENMASK"),
> the code was fine. A broken revert in 1e7933a575ed ("uapi: Revert "bitops: avoid integer overflow in GENMASK(_ULL)"")
> introduced the incorrect usage of BITS_PER_LONG.
> That was fixed in commit 11fcf368506d ("uapi: bitops: use UAPI-safe variant of BITS_PER_LONG again").
> But a broken sync of the kernel headers with the tools/ headers in
> commit fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources")
> undid the fix.
> 
> Reapply the fix and while at it also fix the tools header.
> 
> Fixes: fc92099902fb ("tools headers: Synchronize linux/bits.h with the kernel sources")
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>

Acked-by: Yury Norov (NVIDIA) <yury.norov@...il.com>

Arnaldo, do you want to move it yourself or with my branch?

> ---
>  include/uapi/linux/bits.h       | 4 ++--
>  tools/include/uapi/linux/bits.h | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/uapi/linux/bits.h b/include/uapi/linux/bits.h
> index 682b406e10679dc8baa188830ab0811e7e3e13e3..a04afef9efca42f062e142fcb33f5d267512b1e5 100644
> --- a/include/uapi/linux/bits.h
> +++ b/include/uapi/linux/bits.h
> @@ -4,9 +4,9 @@
>  #ifndef _UAPI_LINUX_BITS_H
>  #define _UAPI_LINUX_BITS_H
>  
> -#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (BITS_PER_LONG - 1 - (h))))
> +#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (__BITS_PER_LONG - 1 - (h))))
>  
> -#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
> +#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (__BITS_PER_LONG_LONG - 1 - (h))))
>  
>  #define __GENMASK_U128(h, l) \
>  	((_BIT128((h)) << 1) - (_BIT128(l)))
> diff --git a/tools/include/uapi/linux/bits.h b/tools/include/uapi/linux/bits.h
> index 682b406e10679dc8baa188830ab0811e7e3e13e3..a04afef9efca42f062e142fcb33f5d267512b1e5 100644
> --- a/tools/include/uapi/linux/bits.h
> +++ b/tools/include/uapi/linux/bits.h
> @@ -4,9 +4,9 @@
>  #ifndef _UAPI_LINUX_BITS_H
>  #define _UAPI_LINUX_BITS_H
>  
> -#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (BITS_PER_LONG - 1 - (h))))
> +#define __GENMASK(h, l) (((~_UL(0)) << (l)) & (~_UL(0) >> (__BITS_PER_LONG - 1 - (h))))
>  
> -#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
> +#define __GENMASK_ULL(h, l) (((~_ULL(0)) << (l)) & (~_ULL(0) >> (__BITS_PER_LONG_LONG - 1 - (h))))
>  
>  #define __GENMASK_U128(h, l) \
>  	((_BIT128((h)) << 1) - (_BIT128(l)))
> 
> ---
> base-commit: d0b3b7b22dfa1f4b515fd3a295b3fd958f9e81af
> change-id: 20250630-uapi-genmask-d36e3ffc5691
> 
> Best regards,
> -- 
> Thomas Weißschuh <thomas.weissschuh@...utronix.de>