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[2001:8b0:dfde:e1a0::2]) by smtp.gmail.com with ESMTPSA id h6sm8030214wrr.21.2021.04.03.12.41.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Apr 2021 12:41:17 -0700 (PDT) Date: Sat, 3 Apr 2021 20:41:15 +0100 From: Phillip Potter To: Eric Dumazet Cc: davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: initialize local variables in net/ipv6/mcast.c and net/ipv4/igmp.c Message-ID: References: <20210402173617.895-1-phil@philpotter.co.uk> <37f4c845-e63b-87b8-29ec-b28d895326cd@gmail.com> <05c984b6-140d-112e-9151-4aea6e8e5a80@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05c984b6-140d-112e-9151-4aea6e8e5a80@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 02, 2021 at 11:12:36PM +0200, Eric Dumazet wrote: > > > On 4/2/21 10:53 PM, Eric Dumazet wrote: > > > > > > On 4/2/21 8:10 PM, Phillip Potter wrote: > >> On Fri, Apr 02, 2021 at 07:49:44PM +0200, Eric Dumazet wrote: > >>> > >>> > >>> On 4/2/21 7:36 PM, Phillip Potter wrote: > >>>> Use memset to initialize two local buffers in net/ipv6/mcast.c, > >>>> and another in net/ipv4/igmp.c. Fixes a KMSAN found uninit-value > >>>> bug reported by syzbot at: > >>>> https://syzkaller.appspot.com/bug?id=0766d38c656abeace60621896d705743aeefed51 > >>> > >>> > >>> According to this link, the bug no longer triggers. > >>> > >>> Please explain why you think it is still there. > >>> > >> > >> Dear Eric, > >> > >> It definitely still triggers, tested it on the master branch of > >> https://github.com/google/kmsan last night. The patch which fixes the > >> crash on that page is the same patch I've sent in. > > > > Please send the full report (stack trace) > > I think your patch just silences the real problem. > > The issue at hand is that TUNSETLINK changes dev->type without making > any change to dev->addr_len > > This is the real issue. > > If you care about this, please fix tun driver. > Dear Eric, Thank you for pointing me in the right direction. I will do as you suggest. Regards, Phil