Re: [PATCH] powerpc/ps3: Fix repository.c build failure

[Thorsten Blum <thorsten.blum@linux.dev>]

On Fri, Jul 31, 2026 at 09:34:28AM +0200, Christophe Leroy (CS GROUP) wrote:
> Le 03/07/2026 à 18:58, Thorsten Blum a écrit :
> > GCC fails to build ps3_defconfig with the following errors:
> > 
> >    arch/powerpc/platforms/ps3/repository.c: In function ‘make_first_field.constprop’:
> >    arch/powerpc/platforms/ps3/repository.c:78:9: error: ‘strnlen’ specified bound 8 exceeds source size 3 [-Werror=stringop-overread]
> >       78 |         memcpy((char *)&n, text, strnlen(text, sizeof(n)));
> >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >    arch/powerpc/platforms/ps3/repository.c: In function ‘make_first_field.constprop’:
> >    arch/powerpc/platforms/ps3/repository.c:78:9: error: ‘strnlen’ specified bound 8 exceeds source size 4 [-Werror=stringop-overread]
> >       78 |         memcpy((char *)&n, text, strnlen(text, sizeof(n)));
> >          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 
> > The current use of strnlen(text, sizeof(n)) triggers -Wstringop-overread
> > when text is a short string literal that is smaller than sizeof(n), such
> > as "bi" or "bus". Use strlen(text) instead and clamp the copy length to
> > sizeof(n) before memcpy().
> > 
> > Drop the redundant char * cast while at it.
> > 
> > Fixes: f94a84a09148 ("powerpc/ps3: refactor strncpy usage")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> > ---
> >   arch/powerpc/platforms/ps3/repository.c | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/platforms/ps3/repository.c b/arch/powerpc/platforms/ps3/repository.c
> > index b8c030eab138..0cc755ac3e7f 100644
> > --- a/arch/powerpc/platforms/ps3/repository.c
> > +++ b/arch/powerpc/platforms/ps3/repository.c
> > @@ -6,6 +6,8 @@
> >    *  Copyright 2006 Sony Corp.
> >    */
> > +#include <linux/minmax.h>
> > +
> >   #include <asm/lv1call.h>
> >   #include "platform.h"
> > @@ -74,8 +76,9 @@ static void _dump_node(unsigned int lpar_id, u64 n1, u64 n2, u64 n3, u64 n4,
> >   static u64 make_first_field(const char *text, u64 index)
> >   {
> >   	u64 n = 0;
> > +	size_t len = min(strlen(text), sizeof(n));
> > -	memcpy((char *)&n, text, strnlen(text, sizeof(n)));
> > +	memcpy(&n, text, len);
> >   	return PS3_VENDOR_ID_NONE + (n >> 32) + index;
> >   }
> 
> Maybe change to u32 and remove the n >> 32.
> 
> Shouldn't the same fix be done in make_field() ?

make_field() has two callers where the compiler can't infer the size
of the string at compile time, so it doesn't produce this error.

make_first_field() is called only with constant strings, which lets the
compiler infer that all string lengths are less than 8 bytes.