From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8C2323D7E6; Fri, 5 Dec 2025 03:22:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764904958; cv=none; b=Va0+cn/F+xwyqNMbL40pifIUMHku4iWpVg/gzuHsQGJiCgTsWaIeUjGRych6b86wjo/HMXa2Dm68+Gln5iikwIzW45nhnZUYnoZ2UwkRepQDSkxSsfY8V5GahYtZ1rq4hEr0FFEMGcCP6o+HAMpNPu9R+btOJ9ErRJg8J5Ljl3A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764904958; c=relaxed/simple; bh=QBrTDsRqo/yw2j45O40D+5dX5EYnM1bJwpbdQGzAzdQ=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=mhhbJ+WsWAvQm0Ns7Ve8M+QbCX/gIM+buXAd6Dn/zvYx0V9hE2T/lBd2aMZkQrWz9bKe6Jgsb/JOgPrAelpdH5QWEQrN+IDapxr8jYw5IMjcjPpMF4ExmWgruRb3AoqI/NEHxCodqL7lrKJnsTjOxux8nnw+K5Innbst0BNin+c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=AXGCPgWd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="AXGCPgWd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C737FC4CEFB; Fri, 5 Dec 2025 03:22:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1764904958; bh=QBrTDsRqo/yw2j45O40D+5dX5EYnM1bJwpbdQGzAzdQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=AXGCPgWd4mydusswaGZKqx4kEvlENRvG/I3+tUFWa0XByeiLMpFRYIlajA9z/nRJr OlYuonufde9e5Fdl6T5Jf96rlSRlq5NLs/fKAvUS2+aIDY2nF+a4qvHLrT5ZwCgzld q4v4GbSKtg0dLAjab3P3ybv7nvWbSbKQ2XgDr0YM= Date: Thu, 4 Dec 2025 19:22:37 -0800 From: Andrew Morton To: Andrey Konovalov Cc: Maciej Wieczor-Retman , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Vincenzo Frascino , Marco Elver , jiayuan.chen@linux.dev, stable@vger.kernel.org, Maciej Wieczor-Retman , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] kasan: Unpoison vms[area] addresses with a common tag Message-Id: <20251204192237.0d7a07c9961843503c08ebab@linux-foundation.org> In-Reply-To: References: <873821114a9f722ffb5d6702b94782e902883fdf.1764874575.git.m.wieczorretman@pm.me> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 5 Dec 2025 02:09:06 +0100 Andrey Konovalov wrote: > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -591,11 +591,28 @@ void __kasan_unpoison_vmap_areas(struct vm_struct **vms, int nr_vms, > > unsigned long size; > > void *addr; > > int area; > > + u8 tag; > > + > > + /* > > + * If KASAN_VMALLOC_KEEP_TAG was set at this point, all vms[] pointers > > + * would be unpoisoned with the KASAN_TAG_KERNEL which would disable > > + * KASAN checks down the line. > > + */ > > + if (flags & KASAN_VMALLOC_KEEP_TAG) { > > I think we can do a WARN_ON() here: passing KASAN_VMALLOC_KEEP_TAG to > this function would be a bug in KASAN annotations and thus a kernel > bug. Therefore, printing a WARNING seems justified. This? --- a/mm/kasan/common.c~kasan-unpoison-vms-addresses-with-a-common-tag-fix +++ a/mm/kasan/common.c @@ -598,7 +598,7 @@ void __kasan_unpoison_vmap_areas(struct * would be unpoisoned with the KASAN_TAG_KERNEL which would disable * KASAN checks down the line. */ - if (flags & KASAN_VMALLOC_KEEP_TAG) { + if (WARN_ON_ONCE(flags & KASAN_VMALLOC_KEEP_TAG)) { pr_warn("KASAN_VMALLOC_KEEP_TAG flag shouldn't be already set!\n"); return; } _