diff mbox series

drivers/perf: Fix some null pointer dereference issues in thunderx2_pmu.c

Message ID 20231211090347.265240-1-chentao@kylinos.cn
State New
Headers
Series drivers/perf: Fix some null pointer dereference issues in thunderx2_pmu.c |

Commit Message

Kunwu Chan Dec. 11, 2023, 9:03 a.m. UTC 
  devm_kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.

Fixes: 69c32972d593 ("drivers/perf: Add Cavium ThunderX2 SoC UNCORE PMU driver")
Cc: Kunwu Chan <kunwu.chan@hotmail.com>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
---
 drivers/perf/thunderx2_pmu.c | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Will Deacon Dec. 12, 2023, 9:25 a.m. UTC | #1 
On Mon, Dec 11, 2023 at 05:03:47PM +0800, Kunwu Chan wrote:
> devm_kasprintf() returns a pointer to dynamically allocated memory
> which can be NULL upon failure.
> 
> Fixes: 69c32972d593 ("drivers/perf: Add Cavium ThunderX2 SoC UNCORE PMU driver")
> Cc: Kunwu Chan <kunwu.chan@hotmail.com>
> Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
> ---
>  drivers/perf/thunderx2_pmu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
> index 1edb9c03704f..07edb174a0d7 100644
> --- a/drivers/perf/thunderx2_pmu.c
> +++ b/drivers/perf/thunderx2_pmu.c
> @@ -742,6 +742,8 @@ static int tx2_uncore_pmu_register(
>  
>  	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
>  			"%s", name);
> +	if (!tx2_pmu->pmu.name)
> +		return -ENOMEM;
>  
>  	return perf_pmu_register(&tx2_pmu->pmu, tx2_pmu->pmu.name, -1);

AFAICT, perf_pmu_register() will WARN and return NULL, so I'm not sure what
we gain from the additional check.

>  }
> @@ -881,6 +883,11 @@ static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
>  		return NULL;
>  	}
>  
> +	if (!tx2_pmu->name) {
> +		dev_err(dev, "PMU type %d: Fail to allocate memory\n", type);
> +		devm_kfree(dev, tx2_pmu);
> +		return NULL;
> +	}

In the _highly_ unlikely even that devm_kasprintf() failed to allocate,
shouldn't we get a splat from the allocator? I don't think it's useful
to print another message.

Will
Kunwu Chan Dec. 14, 2023, 2:57 a.m. UTC | #2 
Thanks for your reply.

After read tx2_uncore_pmu_register again.
 From the defination: 'char *name = tx2_pmu->name;',
we could know 'tx2_pmu->pmu.name' equals 'tx2_pmu->name'

The difference is that a new memory space is allocated for 
'tx2_pmu->pmu.name'.

If 'tx2_pmu->pmu.name' is always the same as 'tx2_pmu->name', whether we 
should use 'tx2_pmu->pmu.name =  tx2_pmu->name;'
to replace the 'devm_kasprintf'.

I'm not sure it's appropriate to do that.

Thanks again.


On 2023/12/12 17:25, Will Deacon wrote:
> On Mon, Dec 11, 2023 at 05:03:47PM +0800, Kunwu Chan wrote:
>> devm_kasprintf() returns a pointer to dynamically allocated memory
>> which can be NULL upon failure.
>>
>> Fixes: 69c32972d593 ("drivers/perf: Add Cavium ThunderX2 SoC UNCORE PMU driver")
>> Cc: Kunwu Chan <kunwu.chan@hotmail.com>
>> Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
>> ---
>>   drivers/perf/thunderx2_pmu.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
>> index 1edb9c03704f..07edb174a0d7 100644
>> --- a/drivers/perf/thunderx2_pmu.c
>> +++ b/drivers/perf/thunderx2_pmu.c
>> @@ -742,6 +742,8 @@ static int tx2_uncore_pmu_register(
>>   
>>   	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
>>   			"%s", name);
>> +	if (!tx2_pmu->pmu.name)
>> +		return -ENOMEM;
>>   
>>   	return perf_pmu_register(&tx2_pmu->pmu, tx2_pmu->pmu.name, -1);
> 
> AFAICT, perf_pmu_register() will WARN and return NULL, so I'm not sure what
> we gain from the additional check.
> 
>>   }
>> @@ -881,6 +883,11 @@ static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
>>   		return NULL;
>>   	}
>>   
>> +	if (!tx2_pmu->name) {
>> +		dev_err(dev, "PMU type %d: Fail to allocate memory\n", type);
>> +		devm_kfree(dev, tx2_pmu);
>> +		return NULL;
>> +	}
> 
> In the _highly_ unlikely even that devm_kasprintf() failed to allocate,
> shouldn't we get a splat from the allocator? I don't think it's useful
> to print another message.
> 
> Will
diff mbox series

Patch

diff --git a/drivers/perf/thunderx2_pmu.c b/drivers/perf/thunderx2_pmu.c
index 1edb9c03704f..07edb174a0d7 100644
--- a/drivers/perf/thunderx2_pmu.c
+++ b/drivers/perf/thunderx2_pmu.c
@@ -742,6 +742,8 @@  static int tx2_uncore_pmu_register(
 
 	tx2_pmu->pmu.name = devm_kasprintf(dev, GFP_KERNEL,
 			"%s", name);
+	if (!tx2_pmu->pmu.name)
+		return -ENOMEM;
 
 	return perf_pmu_register(&tx2_pmu->pmu, tx2_pmu->pmu.name, -1);
 }
@@ -881,6 +883,11 @@  static struct tx2_uncore_pmu *tx2_uncore_pmu_init_dev(struct device *dev,
 		return NULL;
 	}
 
+	if (!tx2_pmu->name) {
+		dev_err(dev, "PMU type %d: Fail to allocate memory\n", type);
+		devm_kfree(dev, tx2_pmu);
+		return NULL;
+	}
 	return tx2_pmu;
 }