From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: net: integer overflow in ip_idents_reserve Date: Tue, 16 Dec 2014 20:15:12 -0500 Message-ID: <5490D920.5000104@oracle.com> References: <5490A1F8.6020207@oracle.com> <1418766460.9773.48.camel@edumazet-glaptop2.roam.corp.google.com> <1418771356.3449499.203748285.4B1A82B8@webmail.messagingengine.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: "David S. Miller" , LKML , netdev@vger.kernel.org, Andrey Ryabinin , Dave Jones To: Hannes Frederic Sowa , Eric Dumazet Return-path: In-Reply-To: <1418771356.3449499.203748285.4B1A82B8@webmail.messagingengine.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 12/16/2014 06:09 PM, Hannes Frederic Sowa wrote: > > On Tue, Dec 16, 2014, at 22:47, Eric Dumazet wrote: >> > On Tue, 2014-12-16 at 16:19 -0500, Sasha Levin wrote: >>> > > Hi Eric, >>> > > >>> > > While fuzzing with trinity on a -next kernel with the undefined behaviour >>> > > sanitizer path, I've observed the following warning in code which was >>> > > introduced in 04ca6973f7 ("ip: make IP identifiers less predictable"): >> > >> > This is a false positive. > Also we compile the whole kernel with -fno-strict-overflow, so every > report of signed overflow leading to undefined behavior is probably a > false positive. I don't know if it is worth to try to get rid of them, I > doubt it. I reported this one because there's usually some code to handle overflow in code that expects that and here there was none (I could see). For example, the ntp code had a few cases where a user could generate overflows and mess up quite a few things (he got what he asked for - problems). Thanks, Sasha