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From: Liam Howlett <liam.howlett@oracle.com>
To: David Hildenbrand <david@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH RFC 5/9] s390/uv: fully validate the VMA before calling follow_page()
Date: Fri, 10 Sep 2021 14:14:12 +0000	[thread overview]
Message-ID: <20210910141404.fzgxymamjnfnvskf@revolver> (raw)
In-Reply-To: <20210909145945.12192-6-david@redhat.com>

* David Hildenbrand <david@redhat.com> [210909 11:01]:
> We should not walk/touch page tables outside of VMA boundaries when
> holding only the mmap sem in read mode. Evil user space can modify the
> VMA layout just before this function runs and e.g., trigger races with
> page table removal code since commit dd2283f2605e ("mm: mmap: zap pages
> with read mmap_sem in munmap").
> 
> find_vma() does not check if the address is >= the VMA start address;
> use vma_lookup() instead.
> 
> Fixes: 214d9bbcd3a6 ("s390/mm: provide memory management functions for protected KVM guests")
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  arch/s390/kernel/uv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
> index aeb0a15bcbb7..193205fb2777 100644
> --- a/arch/s390/kernel/uv.c
> +++ b/arch/s390/kernel/uv.c
> @@ -227,7 +227,7 @@ int gmap_make_secure(struct gmap *gmap, unsigned long gaddr, void *uvcb)
>  	uaddr = __gmap_translate(gmap, gaddr);
>  	if (IS_ERR_VALUE(uaddr))
>  		goto out;
> -	vma = find_vma(gmap->mm, uaddr);
> +	vma = vma_lookup(gmap->mm, uaddr);
>  	if (!vma)
>  		goto out;
>  	/*
> -- 
> 2.31.1
> 
> 

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

  reply	other threads:[~2021-09-10 14:14 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-09 14:59 [PATCH RFC 0/9] s390: fixes, cleanups and optimizations for page table walkers David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 1/9] s390/gmap: validate VMA in __gmap_zap() David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 2/9] s390/gmap: don't unconditionally call pte_unmap_unlock() " David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 3/9] s390/mm: validate VMA in PGSTE manipulation functions David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 4/9] s390/mm: fix VMA and page table handling code in storage key handling functions David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 5/9] s390/uv: fully validate the VMA before calling follow_page() David Hildenbrand
2021-09-10 14:14   ` Liam Howlett [this message]
2021-09-09 14:59 ` [PATCH RFC 6/9] s390/pci_mmio: fully validate the VMA before calling follow_pte() David Hildenbrand
2021-09-10  8:22   ` Niklas Schnelle
2021-09-10  9:23     ` David Hildenbrand
2021-09-10 12:48       ` Niklas Schnelle
2021-09-10 14:12       ` Liam Howlett
2021-09-10 14:31         ` Niklas Schnelle
2021-09-10 14:52           ` Liam Howlett
2021-09-09 14:59 ` [PATCH RFC 7/9] s390/mm: no need for pte_alloc_map_lock() if we know the pmd is present David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 8/9] s390/mm: optimize set_guest_storage_key() David Hildenbrand
2021-09-09 14:59 ` [PATCH RFC 9/9] s390/mm: optimize reset_guest_reference_bit() David Hildenbrand

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