From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793783180; b=nfJHfU4hCn99Qdw+2OvELE/MD2FWusg13sZqVU7thPbWY5u0peUs8sCg8dwrVB5IYf09 yIToiX70rAs5e92K6XiiEAGoAHdiABmNp062slCV5WlIVba7E3vijpWybku+WeLfI5hDg +4y/iX1ccaqKdIOQJ09aNoaNTx8O9njiIhYzLvkcOJbEReSqsnXwb9uEbNb202kQsKvyZ u0e6x6W+BTO/RJLxVxYljZMLj4pxD1pU+JfD/N4sJEjhYOiqU4x36JUpxqm5YRsOI7q1m e/LxRunrXfWZB82TwEg+ncmhAtNl3Ex5TumbuqTVlWKaFji0GMl3DnUaAObWkNj4vTQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793783180; h=Received:DKIM-Signature:Date:From:To:cc:Subject:In-Reply-To: Message-ID:References:MIME-Version:Content-Type; bh=TL+lpd9Tre0F9K5FTT6m3e9RtyKI/GiJUyTb5HPC2e0=; b=wMTBG61MO/tVs2UbbNw5X0d9ouYm93w59PUzz/aLWRK3sx9Ub2b8/m/jRlPPLQd/CkTO GaWMrZ02qwrQHGAeSi/CLEVTAff3lMy5bIeC90Zylen3sLFu0mrFVRndYgWdoKSiDWDGx q7OQgIl589j7iIeXyGpYC26b2T1L6uo8VnXH8lGnx38Mc6tf7AeY/9IHQps7FU0VAY2vF ltsugSX7IxrKHnuoLWuOq+bhRwZoth51wdPCJC8z9ESgEdpfuM/aeed6tvF+Aepzd1DbX sjwCeqdIy6rpMvtjty0j7LhK7XPN00N/pj0z9avztN1VmUyQdcXOEKKz39+hN+/8ODQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OAf+r0nM; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FBF8606A31B for ; Wed, 4 Nov 2026 09:06:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OAf+r0nM Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3541B1F000C1; Wed, 4 Nov 2026 09:06:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793783179; bh=TL+lpd9Tre0F9K5FTT6m3e9RtyKI/GiJUyTb5HPC2e0=; h=Date:From:To:cc:Subject:In-Reply-To:References; b=OAf+r0nM6knPaZzy7i2l3S9Ulid2btsFBPVL8zJPf7pnpRT+28IU4WRY1oYuVtr20 i3pNFR3qpETwc1PaZ4bOwR1qkPW0GVhv+WjybdrfswfTqiMG7lB2zIb7AJAODK7/SK ySKZNzlnuyGX8U9HxctuHaayT42ZfDp/RP1gMEZIVJWnV6ozDZB15x6xaCMqOmrO6E yeJi7aMgq6pPaRL9xwqPLTg1vgiW0arxmbX+uihXXKOSHEvMU+XmmDTvj1XYQ/83Ud zkac7NnUuLafRdhCzNqytng+JNdgo0qOrNJzmZY0ZN1aE+Y2CcFWTWa7pZmprOwWHY jm+rT6f4Zu8Lg== Date: Wed, 4 Nov 2026 02:06:03 -0700 (MST) From: Paul Walmsley To: Michael Ellerman cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: defconfig: Disable COMPAT_BRK In-Reply-To: <20261029-compat-brk-v1-1-5b2cf86eb453@kernel.org> Message-ID: <0b81d999-2aa1-83e3-6dce-e419ec5f55ac@kernel.org> References: <20261029-compat-brk-v1-1-5b2cf86eb453@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Thu, 29 Oct 2026, Michael Ellerman wrote: > COMPAT_BRK defaults to y, which disables brk (heap) randomisation by > default (ie. randomize_va_space=1 by default) for compatibility with > "ancient" binaries, in particular libc5 based binaries. > > libc5 predates RISC-V, so there can't be any libc5 binaries for RISC-V. > > COMPAT_BRK was introduced in 2008, commit 32a932332c8b > ("brk randomization: introduce CONFIG_COMPAT_BRK"). But even then the > only non-libc5 binaries mentioned as being broken were ~5 year old > versions of emacs (see commit c1d171a00294 ("x86: randomize brk")). > > Distro kernels for riscv64 also disable it, including Debian, Fedora, > openSUSE and Ubuntu. So even if there were riscv binaries out there > that rely on it, no mainstream distro would support them. > > Most other architectures already disable COMPAT_BRK in their primary > defconfigs, including arm64, x86_64, powerpc, s390, loongarch and > sparc64, as do the riscv nommu defconfigs. It is also disabled in > kernel/configs/hardening.config. > > So disable COMPAT_BRK in the riscv defconfig so that brk is randomised > by default, matching distro and other arch configs. > > Signed-off-by: Michael Ellerman Thanks, queued for v7.4-rc. - Paul