Re: [PATCH v2 08/34] kasan: only apply __GFP_ZEROTAGS when memory is zeroed
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2021-12-10 17:49:02
Also in:
linux-mm, lkml
On Mon, Dec 06, 2021 at 10:43:45PM +0100, andrey.konovalov@linux.dev wrote:
quoted hunk ↗ jump to hunk
From: Andrey Konovalov <redacted> __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. Signed-off-by: Andrey Konovalov <redacted> Reviewed-by: Alexander Potapenko <glider@google.com> --- mm/kasan/hw_tags.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 0b8225add2e4..c643740b8599 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c@@ -199,11 +199,12 @@ void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags) * 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) {
You can probably leave this unchanged but add a WARN_ON_ONCE() if !init. AFAICT there's only a single place where __GFP_ZEROTAGS is passed. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel