Re: [PATCH] uprobes: use kzalloc to allocate xol area

[Oleg Nesterov]

On 09/03, Sven Schnelle wrote:
>
> To prevent unitialized members, use kzalloc to allocate
> the xol area.
>
> Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxx>

Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>

and since this looks easily exploitable, I'd sugest

Cc: stable@xxxxxxxxxxxxxxx
Fixes: b059a453b1cf1 ("x86/vdso: Add mremap hook to vm_special_mapping")

> ---
>  kernel/events/uprobes.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 73cc47708679..50d7949be2b1 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1489,7 +1489,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
>  	struct xol_area *area;
>  	void *insns;
>  
> -	area = kmalloc(sizeof(*area), GFP_KERNEL);
> +	area = kzalloc(sizeof(*area), GFP_KERNEL);
>  	if (unlikely(!area))
>  		goto out;
>  
> @@ -1499,7 +1499,6 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
>  		goto free_area;
>  
>  	area->xol_mapping.name = "[uprobes]";
> -	area->xol_mapping.fault = NULL;
>  	area->xol_mapping.pages = area->pages;
>  	area->pages[0] = alloc_page(GFP_HIGHUSER);
>  	if (!area->pages[0])
> -- 
> 2.43.0
>