From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: fs: proc: gpf in find_entry Date: Mon, 22 Dec 2014 14:39:54 -0600 Message-ID: <87sig7beqt.fsf@x220.int.ebiederm.org> References: <54982C98.9070806@oracle.com> <87oaqvd6ni.fsf@x220.int.ebiederm.org> <54985F05.2040603@oracle.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Andrey Ryabinin , LKML , linux-fsdevel , Al Viro , "davej \@mail.xmission.com\>\> Dave Jones" To: Sasha Levin Return-path: In-Reply-To: <54985F05.2040603@oracle.com> (Sasha Levin's message of "Mon, 22 Dec 2014 13:12:21 -0500") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Sasha Levin writes: > On 12/22/2014 12:52 PM, Andrey Ryabinin wrote: >> 2014-12-22 18:51 GMT+03:00 Eric W. Biederman : >>> These two instructions: >>>>> 11: 4d 85 ff test %r15,%r15 >>>>> 14: 0f 84 de 01 00 00 je 0x1f8 >>> >>> Should prevent a NULL %r15 value from ever reaching the trapping >>> instruction. >> >> If they were executed, then yes. But I think there was jump from somewhere >> to the instructions below those two. > > There is indeed a jump direct to that point, which avoids the %r15 > check. Where do you see that direct jump, that certainly has not been posted in this thread? There are certainly no such code paths I in the source code. There is only one NULL pointer check in find_entry and it is executed every time the loop executes. So at this point all I know is some set of tools has totally destroyed the code and made what Sasha Levin's is testing so far from the source code that this is a useless bug report. I have no reason to even suspect this bug is actually in the upstream kernel. This appears to be a kind of testing that slows development and wastes peoples time. Can someone give me a patch that sets the TAINTED flag when KASAN is loaded? Eric