From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Subject: kasan: only apply __GFP_ZEROTAGS when memory is zeroed __GFP_ZEROTAGS should only be effective if memory is being zeroed. Currently, hardware tag-based KASAN violates this requirement. Fix by including an initialization check along with checking for __GFP_ZEROTAGS. Link: https://lkml.kernel.org/r/f4f4593f7f675262d29d07c1938db5bd0cd5e285.1643047180.git.andreyknvl@xxxxxxxxxx Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx> Acked-by: Marco Elver <elver@xxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Peter Collingbourne <pcc@xxxxxxxxxx> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kasan/hw_tags.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/kasan/hw_tags.c~kasan-only-apply-__gfp_zerotags-when-memory-is-zeroed +++ a/mm/kasan/hw_tags.c @@ -199,11 +199,12 @@ void kasan_alloc_pages(struct page *page * page_alloc.c. */ bool init = !want_init_on_free() && want_init_on_alloc(flags); + bool init_tags = init && (flags & __GFP_ZEROTAGS); if (flags & __GFP_SKIP_KASAN_POISON) SetPageSkipKASanPoison(page); - if (flags & __GFP_ZEROTAGS) { + if (init_tags) { int i; for (i = 0; i != 1 << order; ++i) _
