diff mbox series

perf/x86/uncore: avoid null-ptr-deref on error in pmu_alloc_topology

Message ID 20240204134841.80003-1-pchelkin@ispras.ru
State New
Headers
Series perf/x86/uncore: avoid null-ptr-deref on error in pmu_alloc_topology |

Commit Message

Fedor Pchelkin Feb. 4, 2024, 1:48 p.m. UTC 
  If topology[die] array allocation fails then topology[die][idx] elements
can't be accessed on error path.

Checking this on the error path probably looks more readable than
decrementing the counter in the allocation loop.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 4d13be8ab5d4 ("perf/x86/intel/uncore: Generalize IIO topology support")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
 arch/x86/events/intel/uncore_snbep.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Liang, Kan Feb. 5, 2024, 3:08 p.m. UTC | #1 
On 2024-02-04 8:48 a.m., Fedor Pchelkin wrote:
> If topology[die] array allocation fails then topology[die][idx] elements
> can't be accessed on error path.
> 
> Checking this on the error path probably looks more readable than
> decrementing the counter in the allocation loop.
> 
> Found by Linux Verification Center (linuxtesting.org).
> 
> Fixes: 4d13be8ab5d4 ("perf/x86/intel/uncore: Generalize IIO topology support")
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> ---

It seems the code just jumps to the wrong kfree on the error path.
Does the below patch work?

diff --git a/arch/x86/events/intel/uncore_snbep.c
b/arch/x86/events/intel/uncore_snbep.c
index 8250f0f59c2b..5481fd00d861 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3808,7 +3808,7 @@ static int pmu_alloc_topology(struct
intel_uncore_type *type, int topology_type)
 	for (die = 0; die < uncore_max_dies(); die++) {
 		topology[die] = kcalloc(type->num_boxes, sizeof(**topology), GFP_KERNEL);
 		if (!topology[die])
-			goto clear;
+			goto free_topology;
 		for (idx = 0; idx < type->num_boxes; idx++) {
 			topology[die][idx].untyped = kcalloc(type->num_boxes,
 							     topology_size[topology_type],
@@ -3827,6 +3827,7 @@ static int pmu_alloc_topology(struct
intel_uncore_type *type, int topology_type)
 			kfree(topology[die][idx].untyped);
 		kfree(topology[die]);
 	}
+free_topology:
 	kfree(topology);
 err:
 	return -ENOMEM;

Thanks,
Kan

>  arch/x86/events/intel/uncore_snbep.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
> index a96496bef678..7d4deb9126be 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -3831,9 +3831,11 @@ static int pmu_alloc_topology(struct intel_uncore_type *type, int topology_type)
>  	return 0;
>  clear:
>  	for (; die >= 0; die--) {
> -		for (idx = 0; idx < type->num_boxes; idx++)
> -			kfree(topology[die][idx].untyped);
> -		kfree(topology[die]);
> +		if (topology[die]) {
> +			for (idx = 0; idx < type->num_boxes; idx++)
> +				kfree(topology[die][idx].untyped);
> +			kfree(topology[die]);
> +		}
>  	}
>  	kfree(topology);
>  err:
Fedor Pchelkin Feb. 5, 2024, 3:18 p.m. UTC | #2 
Hello,

On 24/02/05 10:08AM, Liang, Kan wrote:
> 
> 
> On 2024-02-04 8:48 a.m., Fedor Pchelkin wrote:
> > If topology[die] array allocation fails then topology[die][idx] elements
> > can't be accessed on error path.
> > 
> > Checking this on the error path probably looks more readable than
> > decrementing the counter in the allocation loop.
> > 
> > Found by Linux Verification Center (linuxtesting.org).
> > 
> > Fixes: 4d13be8ab5d4 ("perf/x86/intel/uncore: Generalize IIO topology support")
> > Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> > ---
> 
> It seems the code just jumps to the wrong kfree on the error path.
> Does the below patch work?
> 
> diff --git a/arch/x86/events/intel/uncore_snbep.c
> b/arch/x86/events/intel/uncore_snbep.c
> index 8250f0f59c2b..5481fd00d861 100644
> --- a/arch/x86/events/intel/uncore_snbep.c
> +++ b/arch/x86/events/intel/uncore_snbep.c
> @@ -3808,7 +3808,7 @@ static int pmu_alloc_topology(struct
> intel_uncore_type *type, int topology_type)
>  	for (die = 0; die < uncore_max_dies(); die++) {
>  		topology[die] = kcalloc(type->num_boxes, sizeof(**topology), GFP_KERNEL);
>  		if (!topology[die])
> -			goto clear;
> +			goto free_topology;
>  		for (idx = 0; idx < type->num_boxes; idx++) {
>  			topology[die][idx].untyped = kcalloc(type->num_boxes,
>  							     topology_size[topology_type],
> @@ -3827,6 +3827,7 @@ static int pmu_alloc_topology(struct
> intel_uncore_type *type, int topology_type)
>  			kfree(topology[die][idx].untyped);
>  		kfree(topology[die]);
>  	}
> +free_topology:
>  	kfree(topology);
>  err:
>  	return -ENOMEM;
> 
> Thanks,
> Kan
> 

In this way the already allocated topology[die] elements won't be freed.

--
Fedor
Liang, Kan Feb. 5, 2024, 3:32 p.m. UTC | #3 
On 2024-02-05 10:18 a.m., Fedor Pchelkin wrote:
> Hello,
> 
> On 24/02/05 10:08AM, Liang, Kan wrote:
>>
>>
>> On 2024-02-04 8:48 a.m., Fedor Pchelkin wrote:
>>> If topology[die] array allocation fails then topology[die][idx] elements
>>> can't be accessed on error path.
>>>
>>> Checking this on the error path probably looks more readable than
>>> decrementing the counter in the allocation loop.
>>>
>>> Found by Linux Verification Center (linuxtesting.org).
>>>
>>> Fixes: 4d13be8ab5d4 ("perf/x86/intel/uncore: Generalize IIO topology support")
>>> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
>>> ---
>>
>> It seems the code just jumps to the wrong kfree on the error path.
>> Does the below patch work?
>>
>> diff --git a/arch/x86/events/intel/uncore_snbep.c
>> b/arch/x86/events/intel/uncore_snbep.c
>> index 8250f0f59c2b..5481fd00d861 100644
>> --- a/arch/x86/events/intel/uncore_snbep.c
>> +++ b/arch/x86/events/intel/uncore_snbep.c
>> @@ -3808,7 +3808,7 @@ static int pmu_alloc_topology(struct
>> intel_uncore_type *type, int topology_type)
>>  	for (die = 0; die < uncore_max_dies(); die++) {
>>  		topology[die] = kcalloc(type->num_boxes, sizeof(**topology), GFP_KERNEL);
>>  		if (!topology[die])
>> -			goto clear;
>> +			goto free_topology;
>>  		for (idx = 0; idx < type->num_boxes; idx++) {
>>  			topology[die][idx].untyped = kcalloc(type->num_boxes,
>>  							     topology_size[topology_type],
>> @@ -3827,6 +3827,7 @@ static int pmu_alloc_topology(struct
>> intel_uncore_type *type, int topology_type)
>>  			kfree(topology[die][idx].untyped);
>>  		kfree(topology[die]);
>>  	}
>> +free_topology:
>>  	kfree(topology);
>>  err:
>>  	return -ENOMEM;
>>
>> Thanks,
>> Kan
>>
> 
> In this way the already allocated topology[die] elements won't be freed.
>

Ah, right. The patch looks good to me.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>

Thanks,
Kan
> --
> Fedor
>
diff mbox series

Patch

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index a96496bef678..7d4deb9126be 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -3831,9 +3831,11 @@  static int pmu_alloc_topology(struct intel_uncore_type *type, int topology_type)
 	return 0;
 clear:
 	for (; die >= 0; die--) {
-		for (idx = 0; idx < type->num_boxes; idx++)
-			kfree(topology[die][idx].untyped);
-		kfree(topology[die]);
+		if (topology[die]) {
+			for (idx = 0; idx < type->num_boxes; idx++)
+				kfree(topology[die][idx].untyped);
+			kfree(topology[die]);
+		}
 	}
 	kfree(topology);
 err: