From: Al Viro <viro@ZenIV.linux.org.uk>
To: Paul Mackerras <paulus@ozlabs.org>
Cc: Nixiaoming <nixiaoming@huawei.com>,
David Hildenbrand <david@redhat.com>,
"agraf@suse.com" <agraf@suse.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"rkrcmar@redhat.com" <rkrcmar@redhat.com>,
"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
"kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Re: [PATCH] fix memory leak on kvm_vm_ioctl_create_spapr_tce
Date: Mon, 28 Aug 2017 06:28:08 +0100 [thread overview]
Message-ID: <20170828052808.GH5426@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170828043837.GA12629@fergus.ozlabs.ibm.com>
On Mon, Aug 28, 2017 at 02:38:37PM +1000, Paul Mackerras wrote:
> On Sun, Aug 27, 2017 at 10:02:20PM +0100, Al Viro wrote:
> > On Wed, Aug 23, 2017 at 04:06:24PM +1000, Paul Mackerras wrote:
> >
> > > It seems to me that it would be better to do the anon_inode_getfd()
> > > call before the kvm_get_kvm() call, and go to the fail label if it
> > > fails.
> >
> > And what happens if another thread does close() on the (guessed) fd?
>
> Chaos ensues, but mostly because we don't have proper mutual exclusion
> on the modifications to the list. I'll add a mutex_lock/unlock to
> kvm_spapr_tce_release() and move the anon_inode_getfd() call inside
> the mutex.
>
> It looks like the other possible uses of the fd (mmap, and passing it
> as a parameter to the KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE ioctl on a KVM
> device fd) are safe.
Frankly, it's a lot saner to have "no failure points past anon_inode_getfd()"
policy...
next prev parent reply other threads:[~2017-08-28 5:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-22 14:28 [PATCH] fix memory leak on kvm_vm_ioctl_create_spapr_tce nixiaoming
2017-08-22 15:15 ` David Hildenbrand
2017-08-22 15:23 ` David Hildenbrand
2017-08-23 1:43 ` Nixiaoming
2017-08-23 6:06 ` Paul Mackerras
2017-08-23 8:25 ` David Hildenbrand
2017-08-23 9:16 ` David Hildenbrand
2017-08-23 10:17 ` 答复: " Nixiaoming
2017-08-24 1:06 ` Nixiaoming
2017-08-27 21:02 ` Al Viro
2017-08-28 4:38 ` Paul Mackerras
2017-08-28 5:28 ` Al Viro [this message]
2017-08-28 6:06 ` Paul Mackerras
2017-08-28 11:31 ` Michael Ellerman
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