Re: [PATCH] lib: cpu_rmap.c Refactor allocation size calculation in kzalloc()

[Shuah Khan]

On 9/30/25 03:23, Mehdi Ben Hadj Khelifa wrote:
> Wrap allocation size calculation in size_add() and size_mul() to avoid
> any potential overflow.

How did you find this problem and how did you test this change?
> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@xxxxxxxxx>
> ---
>   lib/cpu_rmap.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
> index f03d9be3f06b..18b2146a73d2 100644
> --- a/lib/cpu_rmap.c
> +++ b/lib/cpu_rmap.c
> @@ -36,7 +36,7 @@ struct cpu_rmap *alloc_cpu_rmap(unsigned int size, gfp_t flags)
>   	obj_offset = ALIGN(offsetof(struct cpu_rmap, near[nr_cpu_ids]),
>   			   sizeof(void *));
>   
> -	rmap = kzalloc(obj_offset + size * sizeof(rmap->obj[0]), flags);
> +	rmap = kzalloc(size_add(obj_offset, size_mul(size, sizeof(rmap->obj[0]))), flags);
>   	if (!rmap)
>   		return NULL;
>   

thanks,
-- Shuah