[PATCH] drivers/perf: Add NULL check in thunderx2_pmu

[Will Deacon]

On Thu, Apr 10, 2025 at 07:20:27PM +0800, Charles Han wrote:
> devm_kasprintf() can return a NULL pointer on failure,but this
> returned value in tx2_uncore_pmu_register() and
> tx2_uncore_pmu_init_dev() is not checked.
> Add NULL check in tx2_uncore_pmu_register() and
> tx2_uncore_pmu_init_dev(), to handle kernel NULL
> pointer dereference error.
> 
> Fixes: 69c32972d593 ("drivers/perf: Add Cavium ThunderX2 SoC UNCORE PMU driver")
> Fixes: 5e2c27e833bb ("drivers/perf: Add CCPI2 PMU support in ThunderX2 UNCORE driver.")
> Signed-off-by: Charles Han <hanchunchao at inspur.com>
> ---
>  drivers/perf/thunderx2_pmu.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
> index 6ed4707bd6bb..03dd297ff326 100644
> --- a/drivers/perf/thunderx2_pmu.c
> +++ b/drivers/perf/thunderx2_pmu.c
> @@ -738,6 +738,8 @@ static int tx2_uncore_pmu_register(
>  
>  	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
>  			"%s", name);
> +	if (!tx2_pmu->pmu.name)
> +		return -ENOMEM;

perf_pmu_register() rejects (and warns) for a NULL name, so I'm not sure
we need to litter the drivers with extra checks.

>  	return perf_pmu_register(&tx2_pmu->pmu, tx2_pmu->pmu.name, -1);
>  }
> @@ -837,6 +839,11 @@ static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
>  		tx2_pmu->attr_groups = l3c_pmu_attr_groups;
>  		tx2_pmu->name = devm_kasprintf(dev, GFP_KERNEL,
>  				"uncore_l3c_%d", tx2_pmu->node);
> +		if (!tx2_pmu->name) {
> +			devm_kfree(dev, tx2_pmu);
> +			return ERR_PTR(-ENOMEM);
> +		}
> +
>  		tx2_pmu->init_cntr_base = init_cntr_base_l3c;
>  		tx2_pmu->start_event = uncore_start_event_l3c;
>  		tx2_pmu->stop_event = uncore_stop_event_l3c;
> @@ -852,6 +859,11 @@ static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
>  		tx2_pmu->attr_groups = dmc_pmu_attr_groups;
>  		tx2_pmu->name = devm_kasprintf(dev, GFP_KERNEL,
>  				"uncore_dmc_%d", tx2_pmu->node);
> +		if (!tx2_pmu->name) {
> +			devm_kfree(dev, tx2_pmu);
> +			return ERR_PTR(-ENOMEM);
> +		}
> +
>  		tx2_pmu->init_cntr_base = init_cntr_base_dmc;
>  		tx2_pmu->start_event = uncore_start_event_dmc;
>  		tx2_pmu->stop_event = uncore_stop_event_dmc;
> @@ -866,6 +878,11 @@ static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
>  		tx2_pmu->attr_groups = ccpi2_pmu_attr_groups;
>  		tx2_pmu->name = devm_kasprintf(dev, GFP_KERNEL,
>  				"uncore_ccpi2_%d", tx2_pmu->node);
> +		if (!tx2_pmu->name) {
> +			devm_kfree(dev, tx2_pmu);
> +			return ERR_PTR(-ENOMEM);
> +		}

Are any of these actually necessary? afaict, the vsprintf code will
emit "(null)" for a NULL pointer.

Will