linux-kernel - Re: Slab-of-out-bounds in search_memslots() in kvm

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Message-ID: <20200417144848.GA13233@linux.intel.com>
Date:   Fri, 17 Apr 2020 07:48:48 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     sam hao <ssesamhao@...il.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com
Subject: Re: Slab-of-out-bounds in search_memslots() in kvm_host.h

On Fri, Apr 17, 2020 at 09:24:10PM +0800, sam hao wrote:
> Hi,
> 
> I've found possible out of bounds access in search_memslots() in kvm_host.h.

...

> if (start < slots->used_slots && gfn >= memslots[start].base_gfn &&
>             gfn < memslots[start].base_gfn + memslots[start].npages) {
>                 atomic_set(&slots->lru_slot, start);
>                 return &memslots[start];
> }

Fixed (with this exact check) by commit b6467ab142b7 ("KVM: Check validity
of resolved slot when searching memslots").  Syzbot found this one very
quickly :-)  Thanks!