On Wed, Feb 02, 2022 at 02:18:25PM -0800, Kees Cook wrote: > GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) > should be treated like a NULL pointer with an offset, and raises > diagnostics when doing bounds checking: > > In function '__memset', > inlined from '__bad_pagetable' at arch/alpha/mm/init.c:79:2: > ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds] > 37 | return __builtin_memset(s, c, n); > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > In function '__memset', > inlined from '__bad_page' at arch/alpha/mm/init.c:86:2: > ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds] > 37 | return __builtin_memset(s, c, n); > | ^~~~~~~~~~~~~~~~~~~~~~~~~ > In function '__memset', > inlined from 'paging_init' at arch/alpha/mm/init.c:256:2: > ./arch/alpha/include/asm/string.h:37:32: error: '__builtin_memset' offset [0, 8191] is out of the bounds [0, 0] [-Werror=array-bounds] > 37 | return __builtin_memset(s, c, n); > > This has been solved in other places[2] already by using the recently > added absolute_pointer() macro. Do the same here. > > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 > [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@xxxxxxxxxxxx/ > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Reviewed-and-tested-by: Guenter Roeck <linux@xxxxxxxxxxxx> > --- > arch/alpha/mm/init.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c > index f6114d03357c..7511723b7669 100644 > --- a/arch/alpha/mm/init.c > +++ b/arch/alpha/mm/init.c > @@ -76,14 +76,14 @@ pgd_alloc(struct mm_struct *mm) > pmd_t * > __bad_pagetable(void) > { > - memset((void *) EMPTY_PGT, 0, PAGE_SIZE); > + memset(absolute_pointer(EMPTY_PGT), 0, PAGE_SIZE); > return (pmd_t *) EMPTY_PGT; > } > > pte_t > __bad_page(void) > { > - memset((void *) EMPTY_PGE, 0, PAGE_SIZE); > + memset(absolute_pointer(EMPTY_PGE), 0, PAGE_SIZE); > return pte_mkdirty(mk_pte(virt_to_page(EMPTY_PGE), PAGE_SHARED)); > } > > @@ -253,7 +253,7 @@ void __init paging_init(void) > free_area_init(max_zone_pfn); > > /* Initialize the kernel's ZERO_PGE. */ > - memset((void *)ZERO_PGE, 0, PAGE_SIZE); > + memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE); > } > > #if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM) > -- > 2.30.2 >
