From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Pavel Machek <pavel@denx.de>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
"Eric Biggers" <ebiggers@kernel.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Paolo Bonzini" <pbonzini@redhat.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Sasha Levin" <sashal@kernel.org>,
syzbot+7857962b4d45e602b8ad@syzkaller.appspotmail.com
Subject: Re: [PATCH 4.19 242/321] kvm: properly check debugfs dentry before using it
Date: Fri, 6 Dec 2019 14:03:48 +0100 [thread overview]
Message-ID: <20191206130348.GC1399220@kroah.com> (raw)
In-Reply-To: <20191205222928.GD25107@duo.ucw.cz>
On Thu, Dec 05, 2019 at 11:29:28PM +0100, Pavel Machek wrote:
> Hi!
>
> > From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > [ Upstream commit 8ed0579c12b2fe56a1fac2f712f58fc26c1dc49b ]
> >
> > debugfs can now report an error code if something went wrong instead of
> > just NULL. So if the return value is to be used as a "real" dentry, it
> > needs to be checked if it is an error before dereferencing it.
> >
> > This is now happening because of ff9fb72bc077 ("debugfs: return error
> > values, not NULL"). syzbot has found a way to trigger multiple debugfs
> > files attempting to be created, which fails, and then the error code
> > gets passed to dentry_path_raw() which obviously does not like it.
>
> 4.19-stable does not contain patch ff9fb72bc077, so is this still good
> idea? It should not break anything, as it still uses IS_ERR_OR_NULL,
> but...
Yes it should as just testing for NULL was incorrect in the first place.
thanks,
greg k-h
prev parent reply other threads:[~2019-12-06 13:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191203223427.103571230@linuxfoundation.org>
2019-12-03 22:35 ` [PATCH 4.19 242/321] kvm: properly check debugfs dentry before using it Greg Kroah-Hartman
2019-12-05 22:29 ` Pavel Machek
2019-12-06 13:03 ` Greg Kroah-Hartman [this message]
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