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 <[email protected]>
Cc: "Rafał Miłecki" <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: [email protected]
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: [email protected]
Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]
Signed-off-by: Kees Cook <[email protected]>
---
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
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 <[email protected]>
> Cc: "Rafał Miłecki" <[email protected]>
> Cc: Thomas Bogendoerfer <[email protected]>
> Cc: [email protected]
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Reported-by: kernel test robot <[email protected]>
> Link: https://lore.kernel.org/lkml/[email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> 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
>
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 <[email protected]>
> Cc: "Rafał Miłecki" <[email protected]>
> Cc: Thomas Bogendoerfer <[email protected]>
> Cc: [email protected]
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Cc: [email protected]
> Reported-by: kernel test robot <[email protected]>
> Link: https://lore.kernel.org/lkml/[email protected]
> Signed-off-by: Kees Cook <[email protected]>
> ---
> 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 ]