Re: [PATCH] coresight: fix resource leaks on path build failure

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 09/11/2026 10:34, James Clark wrote:
> 
> 
> On 09/11/2026 01:24, Jie Gan wrote:
>>
>>
>> On 5/13/2026 9:32 AM, Jie Gan wrote:
>>> Two related leaks when _coresight_build_path() encounters an error after
>>> coresight_grab_device() has already incremented the pm_runtime, module,
>>> and device references for a node:
>>>
>>> 1. In _coresight_build_path(), if kzalloc_obj() for the path node fails
>>>     after coresight_grab_device() succeeds, coresight_drop_device() was
>>>     never called, permanently leaking all three references.
>>>
>>> 2. In coresight_build_path(), on failure the partial path was freed with
>>>     kfree(path) instead of coresight_release_path(path).  kfree() only
>>>     frees the coresight_path struct itself; it does not iterate 
>>> path_list
>>>     to call coresight_drop_device() and kfree() for each coresight_node
>>>     already added by deeper recursive calls, leaking both the 
>>> pm_runtime,
>>>     module, and device references and the node memory for every element
>>>     on the partial path.
>>>
>>> Fix both by adding coresight_drop_device() in the OOM unwind of
>>> _coresight_build_path(), and replacing kfree(path) with
>>> coresight_release_path(path) in coresight_build_path().
>>>
>>> Fixes: 32b0707a4182 ("coresight: Add try_get_module() in 
>>> coresight_grab_device()")
>>> Fixes: b3e94405941e ("coresight: associating path with session rather 
>>> than tracer")
>>> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
>>
>> Gentle ping.
>>
>>> ---
>>>   drivers/hwtracing/coresight/coresight-core.c | 6 ++++--
>>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/ 
>>> hwtracing/coresight/coresight-core.c
>>> index 46f247f73cf6..c1354ea8e11d 100644
>>> --- a/drivers/hwtracing/coresight/coresight-core.c
>>> +++ b/drivers/hwtracing/coresight/coresight-core.c
>>> @@ -825,8 +825,10 @@ static int _coresight_build_path(struct 
>>> coresight_device *csdev,
>>>           return ret;
>>>       node = kzalloc_obj(struct coresight_node);
>>> -    if (!node)
>>> +    if (!node) {
>>> +        coresight_drop_device(csdev);
>>>           return -ENOMEM;
>>> +    }
>>>       node->csdev = csdev;
>>>       list_add(&node->link, &path->path_list);
>>> @@ -851,7 +853,7 @@ struct coresight_path 
>>> *coresight_build_path(struct coresight_device *source,
>>>       rc = _coresight_build_path(source, source, sink, path);
>>>       if (rc) {
>>> -        kfree(path);
>>> +        coresight_release_path(path);
> 
> @Suzuki, there's a conflict here. This will need to be 
> coresight_release_path_locked() if we also take "coresight: etm-perf: 
> Serialize AUX topology access" from my Sashiko fixes.

The changes needed by the patch are already what your patches does.
Apologies Jie Gan, I have merged Jamess series which solves everything.
So, we can ignore this one.

Cheers
Suzuki