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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E822C38A2A for ; Fri, 8 May 2020 12:41:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 25F0020731 for ; Fri, 8 May 2020 12:41:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588941687; bh=AaVBMed/jK2tTG+Zl65dMFrH0jP3Wozb96iodgcBeLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JOLF7CXW4DodBAQ/pHTVdV94r2Pt1m2xtuBUFdsZtd9Tj3c78GZQGM50FT9YuLKhH xYyqAD8/oOUur2RypR94jJa14UHOqmJXM4gu1MCutH/IuhldMHw86pCFM5GSm7+O4U jVXcFfmDj/IWsocQBvtLAE+s6RxDiaI7QRkocWlo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728822AbgEHMl0 (ORCPT ); Fri, 8 May 2020 08:41:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:36304 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728820AbgEHMl0 (ORCPT ); Fri, 8 May 2020 08:41:26 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E15FB2495F; Fri, 8 May 2020 12:41:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588941685; bh=AaVBMed/jK2tTG+Zl65dMFrH0jP3Wozb96iodgcBeLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iqt18IfLeao4MTKZ/+gAq0xrwJwyi4r+K3kLC1a/YpUhji2TFlXwFHbQOlYxwehM0 GqTjYEhMPcJMpofYitve6iNFFgGTGwWosFWIWqQn+uD9Kwx3z5xCQUuJTGR7AtGdGP YREFPklQqfedKgoaLcPqbAgiaFWUZXrfqYIbSNbk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jiri Pirko , "David S. Miller" Subject: [PATCH 4.4 131/312] net: get rid of an signed integer overflow in ip_idents_reserve() Date: Fri, 8 May 2020 14:32:02 +0200 Message-Id: <20200508123133.721321591@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508123124.574959822@linuxfoundation.org> References: <20200508123124.574959822@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet commit adb03115f4590baa280ddc440a8eff08a6be0cb7 upstream. Jiri Pirko reported an UBSAN warning happening in ip_idents_reserve() [] UBSAN: Undefined behaviour in ./arch/x86/include/asm/atomic.h:156:11 [] signed integer overflow: [] -2117905507 + -695755206 cannot be represented in type 'int' Since we do not have uatomic_add_return() yet, use atomic_cmpxchg() so that the arithmetics can be done using unsigned int. Fixes: 04ca6973f7c1 ("ip: make IP identifiers less predictable") Signed-off-by: Eric Dumazet Reported-by: Jiri Pirko Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/route.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -477,12 +477,18 @@ u32 ip_idents_reserve(u32 hash, int segs atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ; u32 old = ACCESS_ONCE(*p_tstamp); u32 now = (u32)jiffies; - u32 delta = 0; + u32 new, delta = 0; if (old != now && cmpxchg(p_tstamp, old, now) == old) delta = prandom_u32_max(now - old); - return atomic_add_return(segs + delta, p_id) - segs; + /* Do not use atomic_add_return() as it makes UBSAN unhappy */ + do { + old = (u32)atomic_read(p_id); + new = old + delta + segs; + } while (atomic_cmpxchg(p_id, old, new) != old); + + return new - segs; } EXPORT_SYMBOL(ip_idents_reserve);