diff mbox series

[resend,RFC,5/9] s390/uv: fully validate the VMA before calling follow_page()

Message ID 20210909162248.14969-6-david@redhat.com (mailing list archive)
State New
Headers show
Series s390: fixes, cleanups and optimizations for page table walkers | expand

Commit Message

David Hildenbrand Sept. 9, 2021, 4:22 p.m. UTC
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(-)

Comments

Claudio Imbrenda Sept. 14, 2021, 4:53 p.m. UTC | #1
On Thu,  9 Sep 2021 18:22:44 +0200
David Hildenbrand <david@redhat.com> wrote:

> 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>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.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;
>  	/*
Liam R. Howlett Sept. 14, 2021, 10:41 p.m. UTC | #2
Reviwed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

* David Hildenbrand <david@redhat.com> [210909 12:23]:
> 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
> 
>
diff mbox series

Patch

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;
 	/*