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 2F7441E9AC7; Thu, 1 Aug 2024 00:40:54 +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=1722472854; cv=none; b=nIwc6SL78rh6KGU0vqBQlwYiAytNjr8IIrudqNmcx51oju5Um2XTRzc3eFFmD9kWZnxbKheiTR95zxL4SgNdxE8iEKmhu9I5EPcz/Amkrp07EaO/eKaZ+NqAEG9cdtYkZc7Rkb3PUg7FGLXqm1Em9e26nH8o/7RM6DE4LMfPRow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722472854; c=relaxed/simple; bh=xpNOueL8LsTpELZTogQwevQccaGHx3UJJeuEUYFzloE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CZtHm8Vb7Sk/SLhp/JXaVlNo+AOg90rsRnhuKkjFEq+zahyIyrVlF5qODC98iXqkp6+NTXPjEW7gCZqGUmmUUdujDA8VbcHFlKECeSR8/i7kAYpVLmyNi4x3fbTTa1jElBg8K1IFW7Mmt5z+BI9YAr4qfH1FBFKVoBshXlpslOo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rxv/ee1S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rxv/ee1S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEC5BC4AF0C; Thu, 1 Aug 2024 00:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722472854; bh=xpNOueL8LsTpELZTogQwevQccaGHx3UJJeuEUYFzloE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rxv/ee1SHz+Ksny0xphP2JbrlQ1bQYVSj5nkxcsPGb44VhbewqzFN2WwYbocvkAH3 c+z5or8FzYcLEScoF30p56VMAps5SrdfmP6xyxWgKcdwQw4gU+5t1RpSGLI87LryFj onn4E/pN3iPWSGOcrMCI37WjF/0tDqeexGX/T6h1Ln/4JHZBn0PSann1dZfB/PVIra 02sHnIwOywCXxVJvq2GVB8sVzyJ7p/fVdnqGJc9YvYWXaH6ZYFaZmL81buJvX3tM/p 9CexARZbm2NVxTf1q5czot9oU2PqMpBWLbl0BMyAhXVkJ54laMWLiJ9VAOGVl8ZPC/ /OyA1qYNDVNZg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Alexey Dobriyan , Kees Cook , Sasha Levin , viro@zeniv.linux.org.uk, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH AUTOSEL 4.19 06/14] ELF: fix kernel.randomize_va_space double read Date: Wed, 31 Jul 2024 20:40:14 -0400 Message-ID: <20240801004037.3939932-6-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240801004037.3939932-1-sashal@kernel.org> References: <20240801004037.3939932-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.19.319 Content-Transfer-Encoding: 8bit From: Alexey Dobriyan [ Upstream commit 2a97388a807b6ab5538aa8f8537b2463c6988bd2 ] ELF loader uses "randomize_va_space" twice. It is sysctl and can change at any moment, so 2 loads could see 2 different values in theory with unpredictable consequences. Issue exactly one load for consistent value across one exec. Signed-off-by: Alexey Dobriyan Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183 Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- fs/binfmt_elf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index c41c568ad1b8a..af8830878fa0b 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -876,7 +876,8 @@ static int load_elf_binary(struct linux_binprm *bprm) if (elf_read_implies_exec(loc->elf_ex, executable_stack)) current->personality |= READ_IMPLIES_EXEC; - if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) + const int snapshot_randomize_va_space = READ_ONCE(randomize_va_space); + if (!(current->personality & ADDR_NO_RANDOMIZE) && snapshot_randomize_va_space) current->flags |= PF_RANDOMIZE; setup_new_exec(bprm); @@ -1136,7 +1137,7 @@ static int load_elf_binary(struct linux_binprm *bprm) current->mm->end_data = end_data; current->mm->start_stack = bprm->p; - if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) { + if ((current->flags & PF_RANDOMIZE) && (snapshot_randomize_va_space > 1)) { /* * For architectures with ELF randomization, when executing * a loader directly (i.e. no interpreter listed in ELF -- 2.43.0