From mboxrd@z Thu Jan 1 00:00:00 1970 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 7EC0DEB64DC for ; Fri, 21 Jul 2023 11:00:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231370AbjGULAE (ORCPT ); Fri, 21 Jul 2023 07:00:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230521AbjGUK7e (ORCPT ); Fri, 21 Jul 2023 06:59:34 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECC262733; Fri, 21 Jul 2023 03:58:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=Url1S2KkTliaPbsKSfxxrI3LXJILvuEJ2CRpOdAeZx4=; b=RjOze5I06m1EPmRzvNMOw4h7zJ 10p45BmFIxxQzO/qLwTkFJsFTB0PrU576kmq0IyFHIfRA75xAexc2xh4dIaNRLa9Y5LNrafe+Y2HU XYyyFWUYwG1XdG7GwrQ8X4aBV8FeMN9VtfhlEzqZaTTa234TXbfT/mP2/kEwc5dwzows9j7EO/zTP 51+OgjfvYfrt/+bUwB908HZKFKqXxSPH9Bxt5Vx+8/i0uds+40kFe/jiU8oYpZzOG2lVwthSuPRLl awEwZyTRVb/2zt01EAaLdTRESfjSw9Qsmle/lZskaj31xN2PyMnVDsz78EP0+awx5ayhv/lILMr2+ U+nM8rUg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qMnqJ-0012OU-K0; Fri, 21 Jul 2023 10:58:40 +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 35687300911; Fri, 21 Jul 2023 12:58:38 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 020DE3157E61D; Fri, 21 Jul 2023 12:58:37 +0200 (CEST) Message-ID: <20230721105743.954526690@infradead.org> User-Agent: quilt/0.66 Date: Fri, 21 Jul 2023 12:22:41 +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 v1 04/14] futex: Validate futex value against futex size References: <20230721102237.268073801@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org 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) --- kernel/futex/futex.h | 8 ++++++++ kernel/futex/syscalls.c | 3 +++ 2 files changed, 11 insertions(+) --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -86,6 +86,14 @@ static inline unsigned int futex_size(un return 1 << size; /* {0,1,2,3} -> {1,2,4,8} */ } +static inline bool futex_validate_input(unsigned int flags, u64 val) +{ + int bits = 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; + if (!futex_validate_input(flags, aux.val)) + return -EINVAL; + futexv[i].w.flags = flags; futexv[i].w.val = aux.val; futexv[i].w.uaddr = aux.uaddr;