From nobody Tue Dec 16 13:26:20 2025 Received: from mail-lf1-f50.google.com (mail-lf1-f50.google.com [209.85.167.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 505A58C1E for ; Fri, 21 Jun 2024 18:54:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.50 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718996095; cv=none; b=VUM2fP6U/m0gWDu5C/lOwmkJUliYlIQPB1MSQDz/0cda44QCptjJ7sZSJb7j4CY8zlBkctrPi/30TSPQJjleRLYRFYL1DcOdOXBbgQmewrX6osgMHZrBxyKRxQ98EGDfkqCGzHv0b/ERo1NCmk8RAEe0mJ7An5m5dYx8d7uufeg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718996095; c=relaxed/simple; bh=ivX5fX2p85CKHxclx7krXad6/Q3yxNvxuPpBL9QM+aY=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=aWgLSDxmElsIagsU0xVHnoFJh6rZZoDk8ceTZhrWlE76wR5ebjSQ6Bog07z/SK/p7iK2F6dFjWH3JdOMVlBhajZ9IhwLZbk1WRQpoGmx+jKDO8uIW5wzFkfU8Rzs2Mujh39ohdIiyQ9YCy+X2rgC6oj267tnU+EFRieD1aTg2ZY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=hcQASuxR; arc=none smtp.client-ip=209.85.167.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hcQASuxR" Received: by mail-lf1-f50.google.com with SMTP id 2adb3069b0e04-52cd8897c73so997651e87.2 for ; Fri, 21 Jun 2024 11:54:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1718996092; x=1719600892; darn=vger.kernel.org; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :from:to:cc:subject:date:message-id:reply-to; bh=lyqC06Vh0EYg26nHAQaeApBBTUbal6sAGqlLXIIM1Eo=; b=hcQASuxRYxpsmvLgKvMHv86u7sOTi07J+dd2vcAfoGvBj/L+QcDqVCsyhnhdQKXocx DUXjBOkCrrIO+hD4JfJy2dcs15Qzd7Ok908pZ2OL5dQUdF1qz5J7cJzMii9nmylAz+5q k1y3CreHDW6AYJi2rYT0v1qOPuaogyT2FI9OjwH+NKo+zEseISaI+uNaPb0BiC0v6jX5 r27aasJqpiNOESH+8pU/QjzL++zyvK3rJO/ZSVC2p1/q+YtC+Mk3WYMK9pI0a6NG0xIs OISNCtVsSHQ6QILB+PohULmvMR3JgBiaJoxDTUuzECIskNJMiCCZ204FSUJZ5s/6/jtm jLYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718996092; x=1719600892; h=content-disposition:mime-version:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=lyqC06Vh0EYg26nHAQaeApBBTUbal6sAGqlLXIIM1Eo=; b=HXcMu18WG6lWoi/xaVMEmQwme4mxu10du08nHRlU/UIROqDEpqo0pXfaBJqe2qL+Cf rdkBl48gXocUb7OskyqQk+N4jMts+tNqcIj19Qn5DH8zaKUz7P6MdRqSUrXRSI+Oz5Du bZhIuebyqczbYB+a3fsnmAADT0XK722x0YJqMf+zaxfNOzwXvj/oCniOpzSNtEf63bKF 9IQC/FYyB0CwMiNcWyL1wtB+ls/RPQD4lyyMJ9q35BhY9caww1Jz1MgT8EmCHqYLzokW n7oKSMLx3aIzygfzS0m0I3GRHoPsdsQdKrgEv5E+oEwsKfWO1F0kaqqdyarrKg34f8yA BTkA== X-Gm-Message-State: AOJu0YyQ0KGiI0pDbwYiJzMpCxutcOLRu1QXuBlVzjbZIxELRM6dJD2F Ui6dvz5nuZ8/jKNQZTIeNpfCKtsA2RN1/X4r9oUoT/w51EGM9oLZhwI+ X-Google-Smtp-Source: AGHT+IGO3w51n4SoCZschdybkDyWkJJCUQM2g9kbc3Bm5J+AUw9OWnStcrfbSd+cBj6Bp0jMK5cUSA== X-Received: by 2002:a05:6512:3441:b0:52c:dc70:ebf8 with SMTP id 2adb3069b0e04-52cdc70ef1emr503637e87.19.1718996092259; Fri, 21 Jun 2024 11:54:52 -0700 (PDT) Received: from p183 ([46.53.254.81]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-57d303da3cbsm1277429a12.16.2024.06.21.11.54.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Jun 2024 11:54:51 -0700 (PDT) Date: Fri, 21 Jun 2024 21:54:50 +0300 From: Alexey Dobriyan To: Eric Biederman , Kees Cook Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org Subject: [PATCH] ELF: fix kernel.randomize_va_space double read Message-ID: <3329905c-7eb8-400a-8f0a-d87cff979b5b@p183> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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.=20 Issue exactly one load for consistent value across one exec. Signed-off-by: Alexey Dobriyan --- fs/binfmt_elf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1003,7 +1003,8 @@ static int load_elf_binary(struct linux_binprm *bprm) if (elf_read_implies_exec(*elf_ex, executable_stack)) current->personality |=3D READ_IMPLIES_EXEC; =20 - if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) + const int snapshot_randomize_va_space =3D READ_ONCE(randomize_va_space); + if (!(current->personality & ADDR_NO_RANDOMIZE) && snapshot_randomize_va_= space) current->flags |=3D PF_RANDOMIZE; =20 setup_new_exec(bprm); @@ -1251,7 +1252,7 @@ static int load_elf_binary(struct linux_binprm *bprm) mm->end_data =3D end_data; mm->start_stack =3D bprm->p; =20 - 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