From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joseph Salisbury Subject: Re: [v3.11][Regression] HID: hyperv: convert alloc+memcpy to memdup Date: Mon, 16 Sep 2013 20:44:05 -0400 Message-ID: <5237A5D5.8010006@canonical.com> References: <5237430B.5040009@canonical.com> <20130916203824.GP25896@mwanda> <52376ED9.5080208@canonical.com> <20130916210503.GQ25896@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130916210503.GQ25896@mwanda> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: driverdev-devel-bounces@linuxdriverproject.org To: Dan Carpenter Cc: list@osuosl.org, Jiri Kosina , Haiyang Zhang , LKML , open@osuosl.org, HID CORE LAYER , devel@linuxdriverproject.org, thomas@m3y3r.de List-Id: linux-input@vger.kernel.org On 09/16/2013 05:05 PM, Dan Carpenter wrote: > On Mon, Sep 16, 2013 at 04:49:29PM -0400, Joseph Salisbury wrote: >> On 09/16/2013 04:38 PM, Dan Carpenter wrote: >>> On Mon, Sep 16, 2013 at 01:42:35PM -0400, Joseph Salisbury wrote: >>>> Reverting the patch changes the driver back to useing kzalloc() and >>>> memcpy() instead of kmemdup. Doing so has uncovered another bug, which >>>> causes an oops on memcpy()[1]. We are in the process of bisecting that >>>> one now and will provide the results. >>> The two bugs are the same it's that the code has shifted a little. Mark >>> the commit as buggy and continue with the git bisect. >>> >>> regards, >>> dan carpenter >> Can you explain a little further? Mark commit a4a23f6 as bad? An >> initial bisect already reported that was the first bad commit, so it >> can't be marked bad. The oops on memcpy() happens after commit a4a23f6 >> is reverted. The oops on memcpy() did not happen before a4a23f6 was >> committed, so I assume this new oops was introduced by a change later. >> >> Right now I'm bisecting down the oops on memcpy() by updating the bisect >> with good or bad, depending if the test kernel hit the oops. I then >> revert a4a23f6, so that revert is the HEAD of the tree each time before >> building the kernel again(As long as the commit spit out by bisect is >> after when a4a23f6 was introduced). > Yep. Please continue bisecting the memcpy() oops. > > kmemdup() is just a kzalloc() followed by a memcpy(). When we split it > apart by reverting the patch then we would expect the oops to move to > the memcpy() part. Somehow "desc" is a bogus pointer, but I don't > immediately see how that is possible. > > regards, > dan carpenter Thanks for the details. We'll continue the bisect and let you know how it goes. Thanks again, Joe