From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: net: llc: NULL ptr deref in llc_ui_sendmsg Date: Fri, 06 Jun 2014 13:53:02 -0400 Message-ID: <5391FFFE.8000100@oracle.com> References: <5391D971.4030001@oracle.com> <20140606154231.GA7629@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: Dave Jones , Arnaldo Carvalho de Melo , "David S. Miller" , "netdev@vger.kernel.org" , LKML Return-path: In-Reply-To: <20140606154231.GA7629@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 06/06/2014 11:42 AM, Dave Jones wrote: > On Fri, Jun 06, 2014 at 11:08:33AM -0400, Sasha Levin wrote: > > Hi all, > > > > While fuzzing with trinity inside a KVM tools guest running the latest -next > > kernel I've stumbled on the following spew: > > > > [ 269.531162] BUG: unable to handle kernel NULL pointer dereference at 000000000000021e > > [ 269.531217] IP: llc_ui_sendmsg (net/llc/af_llc.c:912) > > 905 /* must bind connection to sap if user hasn't done it. */ > 906 if (sock_flag(sk, SOCK_ZAPPED)) { > 907 /* bind to sap with null dev, exclusive. */ > 908 rc = llc_ui_autobind(sock, addr); > 909 if (rc) > 910 goto release; > 911 } > 912 hdrlen = llc->dev->hard_header_len + llc_ui_header_len(sk, addr); > > looks like llc->dev was null, (understandable, given Trinity doesn't really know > how to set up llc beyond random socket()/setsockopt() calls). > > llc_ui_autobind returns -ENODEV in that case, so it looks like the SOCK_ZAPPED test > was false. Something like the patch below maybe ? It feels ugly to be duplicating that > test there, but if this is agreed upon I'll resubmit this properly. I figured it's something more complicated than that since trinity stumbled on it only now and I don't see any code changes in that area. I'll test it with the patch. Thanks, Sasha