From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D31C64963CF; Thu, 13 Aug 2026 16:42:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786639387; cv=none; b=WcpRqN8PF3Rnzu9dr7n1/FkzGyrahaS/Gj23pymo7dukIjYP+0iTWzKqZEFkEbYUvdTWTdR+3dfW/YFVsAB4OWELFBJCbKU5SnMmfUWIvwSRYj+ZYN85n5rdISj7d6cN3MQdkgi+OJCIXM+FiP4DqsEdptvwtHAxyd5RYkOPRKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786639387; c=relaxed/simple; bh=18XYJsZ65BgnVlq3F1zRXJLD6La2O92czJ3L6N1Pe+4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=e45cEs0an5x6vmaBiwn99Cb3wDhk9+4kS7i5l3T2A/l3L/t9CX7bDGQ+ygQmbfIHyGW2UhiyWj33k4oaGas4CTruY4DKUYDlxF5RNLr4YSHYCTeQS9jst9bMEdZoTBZ9dA6XltiUa/bRFucbRz5yZfYbIzpDpXh/Ey/x3aTidH4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=V3/j8n7q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="V3/j8n7q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 965E71F000E9; Thu, 13 Aug 2026 16:42:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786639362; bh=oF5DTKYd+ENE8uJqw+dkx2LAUHD3P6ue7t8VnUrsAXc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=V3/j8n7qqdIchKZjZ8UHxgY/RkOdJSCQxrcTPT3TrRj8GgpWWhpFpblO2M6PAVijO VmNu76ekWMTNjVHRzPr/wtMedGuM/ynS5Bc6QSDq/4v00+So6Q/1J8YAeRFwyjzETo SO3N9PDkyng+RBFJHFUXs4jSUD9w8EJRGWx2DzF5MyXi4gBO7aY4PT0XT1i7t1156L UcGbjSuLYjmFc9YeudfqB0/EYIPwvA4XGLMI6BVUqiOqufrcfvr7pLlbcF+ljcYa1Y 6CvzOqQoZg5fZ8QosKOO5lBRPAAg7ucCBr/SFV4q7cfFEfTnbaThG6suO+ep1mRtOe FqjVHS64wmuLA== Date: Thu, 13 Aug 2026 09:42:42 -0700 From: Kees Cook To: Jaihind Yadav Cc: nathan@kernel.org, nsc@kernel.org, linux-kbuild@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] kstack_erase: suppress -grecord-gcc-switches for external module builds Message-ID: <202608130942.4FFA5AAB9D@keescook> References: <20260803181217.GB1067866@ax162> <20260813082949.1622045-1-jaihindy@qti.qualcomm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260813082949.1622045-1-jaihindy@qti.qualcomm.com> On Thu, Aug 13, 2026 at 01:59:49PM +0530, Jaihind Yadav wrote: > With CONFIG_GCC_PLUGIN_STACKLEAK=y, kstack erase adds: > > -fplugin=$(objtree)/scripts/gcc-plugins/stackleak_plugin.so > > For KBUILD_EXTMOD builds, recording gcc switches can embed this host/build > specific plugin path into module DWARF producer strings, which trips QA > checks looking for absolute path leakage. Isn't this a problem for all Linux gcc plugins, though? -Kees > > Disable gcc switch recording only for external modules by adding > -gno-record-gcc-switches to kstack-erase-cflags when KBUILD_EXTMOD is set. > > This keeps stackleak plugin instrumentation enabled while avoiding leakage > of host-specific paths in external module debug metadata. > > Suggested-by: Nathan Chancellor > Link: https://lore.kernel.org/all/20260803181217.GB1067866@ax162/ > Signed-off-by: Jaihind Yadav > --- > scripts/Makefile.kstack_erase | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/scripts/Makefile.kstack_erase b/scripts/Makefile.kstack_erase > index ee7e4ef7b892..6f31a3915d24 100644 > --- a/scripts/Makefile.kstack_erase > +++ b/scripts/Makefile.kstack_erase > @@ -5,6 +5,7 @@ kstack-erase-cflags-y += -fplugin=$(objtree)/scripts/gcc-plugins/stackleak_plugi > kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_KSTACK_ERASE_TRACK_MIN_SIZE) > kstack-erase-cflags-y += -fplugin-arg-stackleak_plugin-arch=$(SRCARCH) > kstack-erase-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK_VERBOSE) += -fplugin-arg-stackleak_plugin-verbose > +kstack-erase-cflags-$(if $(KBUILD_EXTMOD),y) += -gno-record-gcc-switches > DISABLE_KSTACK_ERASE := -fplugin-arg-stackleak_plugin-disable > endif > > -- > 2.43.0 > > -- Kees Cook