randstruct: disable Clang 15 support

  From: Eric Biggers <ebiggers@google.com>

The randstruct support released in Clang 15 is unsafe to use due to a
bug that can cause miscompilations: "-frandomize-layout-seed
inconsistently randomizes all-function-pointers structs"
(https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
on the Clang 16 release branch, so add a Clang version check.

Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 security/Kconfig.hardening | 3 +++
 1 file changed, 3 insertions(+)


base-commit: 4ec5183ec48656cec489c49f989c508b68b518e3
  

On Tue, Feb 07, 2023 at 10:51:33PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> The randstruct support released in Clang 15 is unsafe to use due to a
> bug that can cause miscompilations: "-frandomize-layout-seed
> inconsistently randomizes all-function-pointers structs"
> (https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
> on the Clang 16 release branch, so add a Clang version check.
> 
> Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  security/Kconfig.hardening | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> index 53baa95cb644f..0f295961e7736 100644
> --- a/security/Kconfig.hardening
> +++ b/security/Kconfig.hardening
> @@ -281,6 +281,9 @@ endmenu
>  
>  config CC_HAS_RANDSTRUCT
>  	def_bool $(cc-option,-frandomize-layout-seed-file=/dev/null)
> +	# Randstruct was first added in Clang 15, but it isn't safe to use until
> +	# Clang 16 due to https://github.com/llvm/llvm-project/issues/60349
> +	depends on !CC_IS_CLANG || CLANG_VERSION >= 160000
>  
>  choice
>  	prompt "Randomize layout of sensitive kernel structures"
> 
> base-commit: 4ec5183ec48656cec489c49f989c508b68b518e3
> -- 
> 2.39.1
> 
>
  

On Wed, Feb 8, 2023 at 6:32 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On Tue, Feb 07, 2023 at 10:51:33PM -0800, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@google.com>
> >
> > The randstruct support released in Clang 15 is unsafe to use due to a
> > bug that can cause miscompilations: "-frandomize-layout-seed
> > inconsistently randomizes all-function-pointers structs"
> > (https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
> > on the Clang 16 release branch, so add a Clang version check.
> >
> > Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
Reviewed-by: Bill Wendling <morbo@google.com>

> > ---
> >  security/Kconfig.hardening | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> > index 53baa95cb644f..0f295961e7736 100644
> > --- a/security/Kconfig.hardening
> > +++ b/security/Kconfig.hardening
> > @@ -281,6 +281,9 @@ endmenu
> >
> >  config CC_HAS_RANDSTRUCT
> >       def_bool $(cc-option,-frandomize-layout-seed-file=/dev/null)
> > +     # Randstruct was first added in Clang 15, but it isn't safe to use until
> > +     # Clang 16 due to https://github.com/llvm/llvm-project/issues/60349
> > +     depends on !CC_IS_CLANG || CLANG_VERSION >= 160000
> >
> >  choice
> >       prompt "Randomize layout of sensitive kernel structures"
> >
> > base-commit: 4ec5183ec48656cec489c49f989c508b68b518e3
> > --
> > 2.39.1
> >
> >
  

On Tue, Feb 7, 2023 at 10:52 PM Eric Biggers <ebiggers@kernel.org> wrote:
>
> From: Eric Biggers <ebiggers@google.com>
>
> The randstruct support released in Clang 15 is unsafe to use due to a
> bug that can cause miscompilations: "-frandomize-layout-seed
> inconsistently randomizes all-function-pointers structs"
> (https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
> on the Clang 16 release branch, so add a Clang version check.
>
> Fixes: 035f7f87b729 ("randstruct: Enable Clang support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Thanks for the patch and report. Guessing that wasn't fun to debug.
Acked-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  security/Kconfig.hardening | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
> index 53baa95cb644f..0f295961e7736 100644
> --- a/security/Kconfig.hardening
> +++ b/security/Kconfig.hardening
> @@ -281,6 +281,9 @@ endmenu
>
>  config CC_HAS_RANDSTRUCT
>         def_bool $(cc-option,-frandomize-layout-seed-file=/dev/null)
> +       # Randstruct was first added in Clang 15, but it isn't safe to use until
> +       # Clang 16 due to https://github.com/llvm/llvm-project/issues/60349
> +       depends on !CC_IS_CLANG || CLANG_VERSION >= 160000
>
>  choice
>         prompt "Randomize layout of sensitive kernel structures"
>
> base-commit: 4ec5183ec48656cec489c49f989c508b68b518e3
> --
> 2.39.1
>
>
  

On Tue, 7 Feb 2023 22:51:33 -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> The randstruct support released in Clang 15 is unsafe to use due to a
> bug that can cause miscompilations: "-frandomize-layout-seed
> inconsistently randomizes all-function-pointers structs"
> (https://github.com/llvm/llvm-project/issues/60349).  It has been fixed
> on the Clang 16 release branch, so add a Clang version check.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] randstruct: disable Clang 15 support
      https://git.kernel.org/kees/c/7ee3819f2ba9