From nobody Thu Sep 11 22:25:24 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 8756CC001B0 for ; Mon, 7 Aug 2023 12:37:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233673AbjHGMhl (ORCPT ); Mon, 7 Aug 2023 08:37:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233603AbjHGMhT (ORCPT ); Mon, 7 Aug 2023 08:37:19 -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 0BA4C10FE; Mon, 7 Aug 2023 05:37:17 -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=1Epi3uPitQ1on7D3YBD3uiLy0TLxJfWf5bL2Vyq95Dw=; b=Co5btgZE3bcLd6z8lfAD2yNF2L ng1KYKs/j+LRyQXyEVivIfQ47vWvqix6Wv8uRYB11Zf6YAPWQ2Kzx6ArCzkOTTWGT+8XCPQ7uXuEW vDAkp51vggTuX10agZQ0yg3W576dARN+M8hwxlyoPwRGjE1XOB0MhUIjhFWN9aJ7vL1eea62cfgP6 NvnVZop5Z9+vAD7rvcXJhH1RecuHIqRh/u8NJKUmTnog33pDpfH/OHUZ4xTe7JYu2pvydxZvXodvi 2IHrCULJhmfjc6eogA90H7UhlDF3UynqeHLBuojaS/A/nCPh7Z4kvOMBaOLWLDVm17tOL1bQyvxXM L0ZUXWwQ==; 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 1qSzTk-003oSd-1J; Mon, 07 Aug 2023 12:36:56 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D1BF4300473; Mon, 7 Aug 2023 14:36:54 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 986A62021C3D7; Mon, 7 Aug 2023 14:36:54 +0200 (CEST) Message-ID: <20230807123323.020870574@infradead.org> User-Agent: quilt/0.66 Date: Mon, 07 Aug 2023 14:18:47 +0200 From: Peter Zijlstra 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 v2 04/14] futex: Validate futex value against futex size References: <20230807121843.710612856@infradead.org> MIME-Version: 1.0 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(+) --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -85,6 +85,16 @@ static inline unsigned int futex_size(un return 1 << (flags & FLAGS_SIZE_MASK); } =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 --- a/kernel/futex/syscalls.c +++ b/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;