Re: [PATCH] uprobes: fix kernel info leak via "[uprobes]" vma

[Google]

On Thu, 26 Sep 2024 18:29:01 +0200
Oleg Nesterov <oleg@xxxxxxxxxx> wrote:

> xol_add_vma() maps the uninitialized page allocated by __create_xol_area()
> into userspace. On some architectures (x86) this memory is readable even
> without VM_READ, VM_EXEC results in the same pgprot_t as VM_EXEC|VM_READ.

Good catch!
I think we push this urgently and send it to stable tree too, right?

Fixes: d4b3b6384f98 ("uprobes/core: Allocate XOL slots for uprobes use")
Cc: stable@xxxxxxxxxxxxxxx

Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Thank you,

> Reported-by: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> ---
>  kernel/events/uprobes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 2ec796e2f055..4b52cb2ae6d6 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1545,7 +1545,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
>  	if (!area->bitmap)
>  		goto free_area;
>  
> -	area->page = alloc_page(GFP_HIGHUSER);
> +	area->page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
>  	if (!area->page)
>  		goto free_bitmap;
>  
> -- 
> 2.25.1.362.g51ebf55
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>