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d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Ze4OYA4kCMJmMvK5z2d/7YkRmJBRmguQKYCL2ja2UL4=; b=yR5wnoj2VIQRptINk1nrlHEkTy2qRpZdOEnvefHafk99HEutq00Ep4+gMIp+Iw0gGB r2RU5Ko/NfHygLihv8sHH4aOAPI8iqnwShq7pcuixcDLFXqbLWj+qDFc8MwOBnJPXmyQ f8RC+Lg6UOv4ozKITKeVCCheDwiqhalk6aub0TO7y2TH56eC6KCnEcbORl0xXeYfvOiw ncWZZ7DcwjlmI8D0BUeDQEUmM+N6YeHFrMxcA5uLhNG1R3vvrTTmzIE7UovjjSnOII58 vafLjlKhsM/KDD3vh4l+R2WZDjAGY1I96Rub7jHA8LUaQEVnTt4UOoSprQCSPcKbO0VB ab3g== X-Gm-Message-State: AOAM533zsATnG4LiV70u6s+gK2YMa1De9SqJoyhuD4wA2lwf1YafnVR+ JnpSFs4Esrv+qI66Xs5oaI9KPcCJHevQPHkFWgyvSw== X-Google-Smtp-Source: ABdhPJwBy5Lmy0e4kFoPzEN++JCwpVABcIGXZw+uIkDEYR9B+YQxC7M1jL4oBMaNz8BbheiS7ZjNinJ1WJCaDQT6kYQ= X-Received: by 2002:a05:620a:d84:: with SMTP id q4mr13046469qkl.610.1638459657279; Thu, 02 Dec 2021 07:40:57 -0800 (PST) MIME-Version: 1.0 References: <938a827f9927ee2112d98e2053ad7764aae9d8f8.1638308023.git.andreyknvl@google.com> In-Reply-To: <938a827f9927ee2112d98e2053ad7764aae9d8f8.1638308023.git.andreyknvl@google.com> From: Alexander Potapenko Date: Thu, 2 Dec 2021 16:40:21 +0100 Message-ID: Subject: Re: [PATCH 07/31] kasan: only apply __GFP_ZEROTAGS when memory is zeroed To: andrey.konovalov@linux.dev Cc: Marco Elver , Vincenzo Frascino , Catalin Marinas , Peter Collingbourne , Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Andrew Morton , linux-mm@kvack.org, Will Deacon , linux-arm-kernel@lists.infradead.org, Evgenii Stepanov , linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 910314002085 X-Stat-Signature: 7xq9gi1jntchcrufii6fffb4ap3axaot Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=pa2nCnfc; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf18.hostedemail.com: domain of glider@google.com designates 209.85.222.174 as permitted sender) smtp.mailfrom=glider@google.com X-HE-Tag: 1638459657-332038 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Nov 30, 2021 at 10:41 PM wrote: > > From: Andrey Konovalov > > __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 Reviewed-by: Alexander Potapenko > --- > 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 =3D !want_init_on_free() && want_init_on_alloc(flags); > + bool init_tags =3D init && (flags & __GFP_ZEROTAGS); > > if (flags & __GFP_SKIP_KASAN_POISON) > SetPageSkipKASanPoison(page); > > - if (flags & __GFP_ZEROTAGS) { > + if (init_tags) { > int i; > > for (i =3D 0; i !=3D 1 << order; ++i) > -- > 2.25.1 > --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg