From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Qian Cai <cai@lca.pw>, Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Marc Zyngier <maz@kernel.org>,
Christoffer Dall <christoffer.dall@arm.com>
Subject: Re: slab-out-of-bounds due to "KVM: Dynamically size memslot array based on number of used slots"
Date: Fri, 20 Mar 2020 12:08:42 -0400 [thread overview]
Message-ID: <20200320160842.GE127076@xz-x1> (raw)
In-Reply-To: <20200320135346.GA16533@linux.intel.com>
On Fri, Mar 20, 2020 at 06:53:46AM -0700, Sean Christopherson wrote:
> On Fri, Mar 20, 2020 at 09:49:03AM -0400, Qian Cai wrote:
> >
> >
> > > On Mar 20, 2020, at 12:34 AM, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> > >
> > > On Thu, Mar 19, 2020 at 11:59:23PM -0400, Qian Cai wrote:
> > >> Reverted the linux-next commit 36947254e5f98 (“KVM: Dynamically size memslot array based on number of used slots”)
> > >> fixed illegal slab object redzone accesses.
> > >>
> > >> [6727.939776][ T1818] BUG: KASAN: slab-out-of-bounds in gfn_to_hva+0xc1/0x2b0 [kvm]
> > >> search_memslots at include/linux/kvm_host.h:1035
> > >
> > > Drat. I'm guessing lru_slot is out of range after a memslot is deleted.
> > > This should fix the issue, though it may not be the most proper fix, e.g.
> > > it might be better to reset lru_slot when deleting a memslot. I'll try and
> > > reproduce tomorrow, unless you can confirm this does the trick.
> >
> > It works fine.
>
> Thanks! I'll send a proper patch in a bit, tweaking a selftest to try and
> hit this as well.
Would resetting lru_slot be better? So to avoid other potential
references to an obsolete lru_slot outside search_memslots(). E.g., I
see that s390 has another function (gfn_to_memslot_approx) used it.
Thanks,
--
Peter Xu
prev parent reply other threads:[~2020-03-20 16:08 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 3:59 slab-out-of-bounds due to "KVM: Dynamically size memslot array based on number of used slots" Qian Cai
2020-03-20 4:34 ` Sean Christopherson
2020-03-20 13:49 ` Qian Cai
2020-03-20 13:53 ` Sean Christopherson
2020-03-20 16:08 ` Peter Xu [this message]
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