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 B0A701E6E70; Thu, 1 Aug 2024 00:40:00 +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=1722472800; cv=none; b=TlEtkQo2xmaRHJWFXJ40nscruV4W8Ayx83i9OSD6oZl/pKzaKYIo4nox2cClaM35cHSgb+DxmEaa/5yh4LDmWuIG0f41JP7VfDp3xoVAknN5cnoxfSOmdnLi16Yg1D4FrZ8XZQVnG5JDYhT9/GQCpfHsj8+13rvgT1MeraKGdZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722472800; c=relaxed/simple; bh=lsmGopSKeK/awEcL9oxaEYbKhcLLMu8DHedaDPU7CEg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iDi49vgPzYlHdUCe1bYL/vQ4uT2JGhY1vLBRtmufxENO3QUU921+8ky7HUsJOtCNXOgddXK8UAQRjnBZxqyRYFOlh+v4ANbyjabAOsWtJn1G9yjTMprIi2J3/pQfbwaWNjWZ0ClFI5b/LL9Zz0ns48ZX3+UgOyK/GNSEa5s/EQo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LOytw9Nh; 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="LOytw9Nh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78826C4AF0C; Thu, 1 Aug 2024 00:39:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722472800; bh=lsmGopSKeK/awEcL9oxaEYbKhcLLMu8DHedaDPU7CEg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LOytw9NhgAb1CNkvhRSeeAZc1HZ2xkTJ0GW1xdqlJt7GcgC3xiIk/u8oyMjo7ii3X 8N7CKbMjXQZEGALKh226ST6xA9dNzapj86AFlIJQki49I2KLH/ABt8Q2OK5mFhzcsd xgn1I6zG5lN7CSn42LuV6GpTXsB6S3gEMxRH/wMemD0fHfEobKVFeVhimRkLCIHboi qas6VxXGxwM0X+IpHbglNNtDrw2UWCW2SjEqk5KL6hNlHC1KDEIYQkbZuDy2tKVFm3 q+d2BSTf9tJam5Gg3Cl9+gcKjoktuvWbndYbrwN6ViZPH4ybhdl1ILPnwAeB3cvbqR WHZuxgvjN3GNQ== 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 5.4 12/22] ELF: fix kernel.randomize_va_space double read Date: Wed, 31 Jul 2024 20:38:41 -0400 Message-ID: <20240801003918.3939431-12-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240801003918.3939431-1-sashal@kernel.org> References: <20240801003918.3939431-1-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 5.4.281 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 72cd871544ac0..33c323a2ccb19 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -854,7 +854,8 @@ 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); @@ -1106,7 +1107,7 @@ 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