From nobody Thu Sep 11 22:42:30 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56B81E7D0A2 for ; Thu, 21 Sep 2023 20:21:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231747AbjIUUVt (ORCPT ); Thu, 21 Sep 2023 16:21:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231601AbjIUUVU (ORCPT ); Thu, 21 Sep 2023 16:21:20 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8CD69038; Thu, 21 Sep 2023 10:31:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=yq6smcRh9Lt9PMXVlulhUee9kIX8B6TjEGtSPSAL3jI=; b=MFTg6cMl019oUQu6rDJgts+aeg 6Z+T8mLRp+uO7oQYQZw8Sm7/bPEVJfCOG+aED2yludqPec99o8HNyZPS/UwxNUu5ybxaL1HEhSQAn dbGtduFHWOeo64tStINJ7gZdIll94CL1nBUWrJCIh7duiDqXpGEwJDGf9UmYQHjclLEG2htYks1j2 k3TT1ZVJmPhNPbii9Vmr15VGN96F+S0BqQB8o5Be51SKNksVDbNp+cdAzrwSIkN9YnEHdQHtiZs0o FsdMmqM6DHVtTYVFoqyyPUjpMHPB4elIcHz6Lly3U5MtaUc3UieSMAgJP1uokBuXVd99H5hXDY8TC QnNwNEBg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qjHQJ-00FJvh-0q; Thu, 21 Sep 2023 11:00:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id E37B2300513; Thu, 21 Sep 2023 13:00:42 +0200 (CEST) Message-Id: <20230921105247.828934099@noisy.programming.kicks-ass.net> User-Agent: quilt/0.65 Date: Thu, 21 Sep 2023 12:45:09 +0200 From: peterz@infradead.org To: tglx@linutronix.de, axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com, dvhart@infradead.org, dave@stgolabs.net, andrealmeid@igalia.com, Andrew Morton , urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com, Arnd Bergmann , linux-api@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, malteskarupke@web.de Subject: [PATCH v3 04/15] futex: Validate futex value against futex size References: <20230921104505.717750284@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline; filename=peterz-futex2-enforce-bits.patch Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Ensure the futex value fits in the given futex size. Since this adds a constraint to an existing syscall, it might possibly change behaviour. Currently the value would be truncated to a u32 and any high bits would get silently lost. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Thomas Gleixner --- kernel/futex/futex.h | 10 ++++++++++ kernel/futex/syscalls.c | 3 +++ 2 files changed, 13 insertions(+) Index: linux-2.6/kernel/futex/futex.h =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-2.6.orig/kernel/futex/futex.h +++ linux-2.6/kernel/futex/futex.h @@ -85,6 +85,16 @@ static inline bool futex_flags_valid(uns return true; } =20 +static inline bool futex_validate_input(unsigned int flags, u64 val) +{ + int bits =3D 8 * futex_size(flags); + + if (bits < 64 && (val >> bits)) + return false; + + return true; +} + #ifdef CONFIG_FAIL_FUTEX extern bool should_fail_futex(bool fshared); #else Index: linux-2.6/kernel/futex/syscalls.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- linux-2.6.orig/kernel/futex/syscalls.c +++ linux-2.6/kernel/futex/syscalls.c @@ -209,6 +209,9 @@ static int futex_parse_waitv(struct fute if (!futex_flags_valid(flags)) return -EINVAL; =20 + if (!futex_validate_input(flags, aux.val)) + return -EINVAL; + futexv[i].w.flags =3D flags; futexv[i].w.val =3D aux.val; futexv[i].w.uaddr =3D aux.uaddr;