Re: [PATCH] vmalloc: Fix NULL pointer dereference in is_vm_area_hugepages()

[Dev Jain <dev.jain@arm.com>]

On 29/05/26 7:11 am, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@kylinos.cn>
> 
> find_vm_area() can return NULL if the given address is not a valid
> vmalloc area. Check the return value before dereferencing it to avoid
> a kernel crash.
> 
> Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
> Signed-off-by: Hui Zhu <zhuhui@kylinos.cn>
> ---

I think this makes sense from API PoV.

Reviewed-by: Dev Jain <dev.jain@arm.com>

>  include/linux/vmalloc.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 3b02c0c6b371..d87dc7f77f4e 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -265,7 +265,9 @@ static inline bool is_vm_area_hugepages(const void *addr)
>  	 * allocated in the vmalloc layer.
>  	 */
>  #ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
> -	return find_vm_area(addr)->page_order > 0;
> +	struct vm_struct *area = find_vm_area(addr);
> +
> +	return area && area->page_order > 0;
>  #else
>  	return false;
>  #endif