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From: Baoquan He <bhe@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dave Young <dyoung@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Philipp Rudo <prudo@redhat.com>,
	kexec@lists.infradead.org, Linux MM <linux-mm@kvack.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v1] proc/vmcore: fix clearing user buffer by properly using clear_user()
Date: Fri, 12 Nov 2021 21:23:26 +0800	[thread overview]
Message-ID: <20211112132326.GA16071@MiWiFi-R3L-srv> (raw)
In-Reply-To: <CADFyXm7uS3GN1AnF-iLpUZMFK=MwF3=NGwSZFqXPA+kK182-cQ@mail.gmail.com>

On 11/12/21 at 10:08am, David Hildenbrand wrote:
> > > "that allows supervisor mode programs to optionally set user-space
> > > memory mappings so that access to those mappings from supervisor mode
> > > will cause a trap. This makes it harder for malicious programs to
> > > "trick" the kernel into using instructions or data from a user-space
> > > program"
> >
> > OK, probably. I thought it's triggered in access_ok(), and tried to
> > figure out why. But seems we should do something to check this in
> > access_ok(), otherwise the logic of clear_user/_clear_user is not so
> > reasonable. Anyway, I have learned it, thanks a lot for digging it out.
> >
> > By the way, I can't open above wiki article, found below commit from
> > hpa. Maybe we can add some into log to tell this, not strong opinin,
> > leave it to you.
> 
> Yes, now that we know the root cause I'll add some more details to the
> patch description and resend -- thanks Baoquan!

Thanks for sending v2.


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WARNING: multiple messages have this Message-ID (diff)
From: Baoquan He <bhe@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dave Young <dyoung@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Philipp Rudo <prudo@redhat.com>,
	kexec@lists.infradead.org, Linux MM <linux-mm@kvack.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v1] proc/vmcore: fix clearing user buffer by properly using clear_user()
Date: Fri, 12 Nov 2021 21:23:26 +0800	[thread overview]
Message-ID: <20211112132326.GA16071@MiWiFi-R3L-srv> (raw)
In-Reply-To: <CADFyXm7uS3GN1AnF-iLpUZMFK=MwF3=NGwSZFqXPA+kK182-cQ@mail.gmail.com>

On 11/12/21 at 10:08am, David Hildenbrand wrote:
> > > "that allows supervisor mode programs to optionally set user-space
> > > memory mappings so that access to those mappings from supervisor mode
> > > will cause a trap. This makes it harder for malicious programs to
> > > "trick" the kernel into using instructions or data from a user-space
> > > program"
> >
> > OK, probably. I thought it's triggered in access_ok(), and tried to
> > figure out why. But seems we should do something to check this in
> > access_ok(), otherwise the logic of clear_user/_clear_user is not so
> > reasonable. Anyway, I have learned it, thanks a lot for digging it out.
> >
> > By the way, I can't open above wiki article, found below commit from
> > hpa. Maybe we can add some into log to tell this, not strong opinin,
> > leave it to you.
> 
> Yes, now that we know the root cause I'll add some more details to the
> patch description and resend -- thanks Baoquan!

Thanks for sending v2.


  reply	other threads:[~2021-11-12 13:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-11 19:18 [PATCH v1] proc/vmcore: fix clearing user buffer by properly using clear_user() David Hildenbrand
2021-11-11 19:18 ` David Hildenbrand
2021-11-12  7:01 ` Baoquan He
2021-11-12  7:01   ` Baoquan He
2021-11-12  8:16   ` David Hildenbrand
2021-11-12  8:16     ` David Hildenbrand
2021-11-12  9:01     ` Baoquan He
2021-11-12  9:01       ` Baoquan He
2021-11-12  9:08       ` David Hildenbrand
2021-11-12  9:08         ` David Hildenbrand
2021-11-12 13:23         ` Baoquan He [this message]
2021-11-12 13:23           ` Baoquan He

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