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* [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *)
@ 2022-09-07 23:05 Kees Cook
  2022-09-08 12:22 ` Gustavo A. R. Silva
  2022-09-19 14:49 ` Thomas Bogendoerfer
  0 siblings, 2 replies; 3+ messages in thread
From: Kees Cook @ 2022-09-07 23:05 UTC (permalink / raw)
  To: Hauke Mehrtens
  Cc: Kees Cook, Rafał Miłecki, Thomas Bogendoerfer,
	linux-mips, Nathan Chancellor, Nick Desaulniers, llvm,
	kernel test robot, Tom Rix, linux-kernel, linux-hardening

Clang is especially sensitive about argument type matching when using
__overloaded functions (like memcmp(), etc). Help it see that function
pointers are just "void *". Avoids this error:

arch/mips/bcm47xx/prom.c:89:8: error: no matching function for call to 'memcmp'
                   if (!memcmp(prom_init, prom_init + mem, 32))
                        ^~~~~~
include/linux/string.h:156:12: note: candidate function not viable: no known conversion from 'void (void)' to 'const void *' for 1st argument extern int memcmp(const void *,const void *,__kernel_size_t);

Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: "Rafał Miłecki" <zajec5@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@vger.kernel.org
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: llvm@lists.linux.dev
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202209080652.sz2d68e5-lkp@intel.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 arch/mips/bcm47xx/prom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/bcm47xx/prom.c b/arch/mips/bcm47xx/prom.c
index ab203e66ba0d..eb5c04a24531 100644
--- a/arch/mips/bcm47xx/prom.c
+++ b/arch/mips/bcm47xx/prom.c
@@ -86,7 +86,7 @@ static __init void prom_init_mem(void)
 			pr_debug("Assume 128MB RAM\n");
 			break;
 		}
-		if (!memcmp(prom_init, prom_init + mem, 32))
+		if (!memcmp((void *)prom_init, (void *)prom_init + mem, 32))
 			break;
 	}
 	lowmem = mem;
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *)
  2022-09-07 23:05 [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *) Kees Cook
@ 2022-09-08 12:22 ` Gustavo A. R. Silva
  2022-09-19 14:49 ` Thomas Bogendoerfer
  1 sibling, 0 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2022-09-08 12:22 UTC (permalink / raw)
  To: Kees Cook
  Cc: Hauke Mehrtens, Rafał Miłecki, Thomas Bogendoerfer,
	linux-mips, Nathan Chancellor, Nick Desaulniers, llvm,
	kernel test robot, Tom Rix, linux-kernel, linux-hardening

On Wed, Sep 07, 2022 at 04:05:56PM -0700, Kees Cook wrote:
> Clang is especially sensitive about argument type matching when using
> __overloaded functions (like memcmp(), etc). Help it see that function
> pointers are just "void *". Avoids this error:
> 
> arch/mips/bcm47xx/prom.c:89:8: error: no matching function for call to 'memcmp'
>                    if (!memcmp(prom_init, prom_init + mem, 32))
>                         ^~~~~~
> include/linux/string.h:156:12: note: candidate function not viable: no known conversion from 'void (void)' to 'const void *' for 1st argument extern int memcmp(const void *,const void *,__kernel_size_t);
> 

Don't we have the same problem at line 162?

(next-20220908)arch/mips/bcm47xx/prom.c:
161         for (extmem = 128 << 20; extmem < 512 << 20; extmem <<= 1) {
162                 if (!memcmp(prom_init, (void *)(off + extmem), 16))
163                         break;
164         }

--
Gustavo

> Cc: Hauke Mehrtens <hauke@hauke-m.de>
> Cc: "Rafał Miłecki" <zajec5@gmail.com>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: linux-mips@vger.kernel.org
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: llvm@lists.linux.dev
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/lkml/202209080652.sz2d68e5-lkp@intel.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/mips/bcm47xx/prom.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/bcm47xx/prom.c b/arch/mips/bcm47xx/prom.c
> index ab203e66ba0d..eb5c04a24531 100644
> --- a/arch/mips/bcm47xx/prom.c
> +++ b/arch/mips/bcm47xx/prom.c
> @@ -86,7 +86,7 @@ static __init void prom_init_mem(void)
>  			pr_debug("Assume 128MB RAM\n");
>  			break;
>  		}
> -		if (!memcmp(prom_init, prom_init + mem, 32))
> +		if (!memcmp((void *)prom_init, (void *)prom_init + mem, 32))
>  			break;
>  	}
>  	lowmem = mem;
> -- 
> 2.34.1
> 

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *)
  2022-09-07 23:05 [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *) Kees Cook
  2022-09-08 12:22 ` Gustavo A. R. Silva
@ 2022-09-19 14:49 ` Thomas Bogendoerfer
  1 sibling, 0 replies; 3+ messages in thread
From: Thomas Bogendoerfer @ 2022-09-19 14:49 UTC (permalink / raw)
  To: Kees Cook
  Cc: Hauke Mehrtens, Rafał Miłecki, linux-mips,
	Nathan Chancellor, Nick Desaulniers, llvm, kernel test robot,
	Tom Rix, linux-kernel, linux-hardening

On Wed, Sep 07, 2022 at 04:05:56PM -0700, Kees Cook wrote:
> Clang is especially sensitive about argument type matching when using
> __overloaded functions (like memcmp(), etc). Help it see that function
> pointers are just "void *". Avoids this error:
> 
> arch/mips/bcm47xx/prom.c:89:8: error: no matching function for call to 'memcmp'
>                    if (!memcmp(prom_init, prom_init + mem, 32))
>                         ^~~~~~
> include/linux/string.h:156:12: note: candidate function not viable: no known conversion from 'void (void)' to 'const void *' for 1st argument extern int memcmp(const void *,const void *,__kernel_size_t);
> 
> Cc: Hauke Mehrtens <hauke@hauke-m.de>
> Cc: "Rafał Miłecki" <zajec5@gmail.com>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: linux-mips@vger.kernel.org
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: llvm@lists.linux.dev
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/lkml/202209080652.sz2d68e5-lkp@intel.com
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/mips/bcm47xx/prom.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/bcm47xx/prom.c b/arch/mips/bcm47xx/prom.c
> index ab203e66ba0d..eb5c04a24531 100644
> --- a/arch/mips/bcm47xx/prom.c
> +++ b/arch/mips/bcm47xx/prom.c
> @@ -86,7 +86,7 @@ static __init void prom_init_mem(void)
>  			pr_debug("Assume 128MB RAM\n");
>  			break;
>  		}
> -		if (!memcmp(prom_init, prom_init + mem, 32))
> +		if (!memcmp((void *)prom_init, (void *)prom_init + mem, 32))
>  			break;
>  	}
>  	lowmem = mem;
> -- 
> 2.34.1

applied to mips-next with the second memcmp(prom_init changed as well.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-09-19 15:44 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-09-07 23:05 [PATCH] MIPS: BCM47XX: Cast memcmp() of function to (void *) Kees Cook
2022-09-08 12:22 ` Gustavo A. R. Silva
2022-09-19 14:49 ` Thomas Bogendoerfer

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