Re: [PATCH net v2 2/3] dpll: fix xa_alloc_cyclic() error handling

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 12/03/2025 09:52, Michal Swiatkowski wrote:
> In case of returning 1 from xa_alloc_cyclic() (wrapping) ERR_PTR(1) will
> be returned, which will cause IS_ERR() to be false. Which can lead to
> dereference not allocated pointer (pin).
> 
> Fix it by checking if err is lower than zero.
> 
> This wasn't found in real usecase, only noticed. Credit to Pierre.
> 
> Fixes: 97f265ef7f5b ("dpll: allocate pin ids in cycle")
> Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
> ---
>   drivers/dpll/dpll_core.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
> index 32019dc33cca..1877201d1aa9 100644
> --- a/drivers/dpll/dpll_core.c
> +++ b/drivers/dpll/dpll_core.c
> @@ -505,7 +505,7 @@ dpll_pin_alloc(u64 clock_id, u32 pin_idx, struct module *module,
>   	xa_init_flags(&pin->parent_refs, XA_FLAGS_ALLOC);
>   	ret = xa_alloc_cyclic(&dpll_pin_xa, &pin->id, pin, xa_limit_32b,
>   			      &dpll_pin_xa_id, GFP_KERNEL);
> -	if (ret)
> +	if (ret < 0)
>   		goto err_xa_alloc;
>   	return pin;
>   err_xa_alloc:

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>