Received-SPF: pass (google.com: domain of linux-kernel+bounces-188654-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Date: Fri, 24 May 2024 13:47:14 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: quic_zijuhu <quic_zijuhu@quicinc.com>
Cc: rafael@kernel.org, akpm@linux-foundation.org, dmitry.torokhov@gmail.com,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] kobject_uevent: Fix OOB access within zap_modalias_env()
Message-ID: <2024052405-award-recycling-6931@gregkh>
References: <1716524403-5415-1-git-send-email-quic_zijuhu@quicinc.com>
 <2024052418-casket-partition-c143@gregkh>
 <74465bf5-ca18-45f8-a881-e95561c59a02@quicinc.com>
 <2024052438-hesitate-chevron-dbd7@gregkh>
 <5acce173-0224-4a05-ae88-3eb1833fcb39@quicinc.com>
 <2024052458-unleash-atom-489b@gregkh>
 <0b916393-eb39-4467-9c99-ac1bc9746512@quicinc.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <0b916393-eb39-4467-9c99-ac1bc9746512@quicinc.com>

On Fri, May 24, 2024 at 05:08:06PM +0800, quic_zijuhu wrote:
> On 5/24/2024 2:56 PM, Greg KH wrote:
> > On Fri, May 24, 2024 at 01:34:49PM +0800, quic_zijuhu wrote:
> >> On 5/24/2024 1:21 PM, Greg KH wrote:
> >>> On Fri, May 24, 2024 at 01:15:01PM +0800, quic_zijuhu wrote:
> >>>> On 5/24/2024 12:33 PM, Greg KH wrote:
> >>>>> On Fri, May 24, 2024 at 12:20:03PM +0800, Zijun Hu wrote:
> >>>>>> zap_modalias_env() wrongly calculates size of memory block
> >>>>>> to move, so maybe cause OOB memory access issue, fixed by
> >>>>>> correcting size to memmove.
> >>>>>
> >>>>> "maybe" or "does"?  That's a big difference :)
> >>>>>
> >>>> i found this issue by reading code instead of really meeting this issue.
> >>>> this issue should be prone to happen if there are more than 1 other
> >>>> environment vars.
> >>>
> >>> But does it?  Given that we have loads of memory checkers, and I haven't
> >>> ever seen any report of any overrun, it would be nice to be sure.
> >>>
> >> yes. if @env includes env vairable MODALIAS and  more than one other env
> >> vairables. then (env->buflen - len) must be greater that actual size of
> >> "target block" shown previously, so the OOB issue must happen.
> > 
> > Then why are none of the tools that we have for catching out-of-bound
> > issues triggered here?  Are the tools broken or is this really just not
> > ever happening?  It would be good to figure that out...
> > 
> don't know why. perhaps, need to report our case to expert of tools.

Try running them yourself and see!