[v2] mm: expand mmap_prepare functionality and usage

[PATCH v2 16/16] mm: on remap assert that input range within the proposed VMA

Posted by Lorenzo Stoakes (Oracle) 3 weeks ago

Now we have range_in_vma_desc(), update remap_pfn_range_prepare() to check
whether the input range in contained within the specified VMA, so we can
fail at prepare time if an invalid range is specified.

This covers the I/O remap mmap actions also which ultimately call into this
function, and other mmap action types either already span the full VMA or
check this already.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
 mm/memory.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 849d5d9eeb83..de0dd17759e2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3142,6 +3142,9 @@ int remap_pfn_range_prepare(struct vm_area_desc *desc)
 	const bool is_cow = vma_desc_is_cow_mapping(desc);
 	int err;
 
+	if (!range_in_vma_desc(desc, start, end))
+		return -EFAULT;
+
 	err = get_remap_pgoff(is_cow, start, end, desc->start, desc->end, pfn,
 			      &desc->pgoff);
 	if (err)
-- 
2.53.0

Re: [PATCH v2 16/16] mm: on remap assert that input range within the proposed VMA

Posted by Suren Baghdasaryan 2 weeks, 5 days ago

On Mon, Mar 16, 2026 at 2:14 PM Lorenzo Stoakes (Oracle) <ljs@kernel.org> wrote:
>
> Now we have range_in_vma_desc(), update remap_pfn_range_prepare() to check
> whether the input range in contained within the specified VMA, so we can

s/in contained/is contained

> fail at prepare time if an invalid range is specified.
>
> This covers the I/O remap mmap actions also which ultimately call into this
> function, and other mmap action types either already span the full VMA or
> check this already.
>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  mm/memory.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 849d5d9eeb83..de0dd17759e2 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3142,6 +3142,9 @@ int remap_pfn_range_prepare(struct vm_area_desc *desc)
>         const bool is_cow = vma_desc_is_cow_mapping(desc);
>         int err;
>
> +       if (!range_in_vma_desc(desc, start, end))
> +               return -EFAULT;
> +
>         err = get_remap_pgoff(is_cow, start, end, desc->start, desc->end, pfn,
>                               &desc->pgoff);
>         if (err)
> --
> 2.53.0
>