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Message-ID: <f04cb594-bd3e-9d8d-e694-dbe059a3744b@arm.com>
Date: Thu, 17 Aug 2023 15:47:54 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Junhao He <hejunhao3@...wei.com>, mike.leach@...aro.org,
leo.yan@...aro.org, james.clark@....com
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linuxarm@...wei.com,
jonathan.cameron@...wei.com, yangyicong@...wei.com,
prime.zeng@...ilicon.com
Subject: Re: [PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list
On 17/08/2023 15:39, Suzuki K Poulose wrote:
> On 17/08/2023 09:59, Junhao He wrote:
>> There are memory leaks reported by kmemleak:
>> ...
>> unreferenced object 0xffff2020103c3200 (size 256):
>> comm "insmod", pid 4476, jiffies 4294978252 (age 50072.536s)
>> hex dump (first 32 bytes):
>> 10 60 40 06 28 20 ff ff 10 c0 59 06 20 20 ff ff .`@.( ....Y. ..
>> 10 e0 47 06 28 20 ff ff 10 00 49 06 28 20 ff ff ..G.( ....I.( ..
>> backtrace:
>> [<0000000034ec4724>] __kmem_cache_alloc_node+0x2f8/0x348
>> [<0000000057fbc15d>] __kmalloc_node_track_caller+0x5c/0x110
>> [<00000055d5e34b>] krealloc+0x8c/0x178
>> [<00000000a4635beb>] coresight_alloc_device_name+0x128/0x188
>> [coresight]
>> [<00000000a92ddfee>] funnel_cs_ops+0x10/0xfffffffffffedaa0
>> [coresight_funnel]
>> [<00000000449e20f8>] dynamic_funnel_ids+0x80/0xfffffffffffed840
>> [coresight_funnel]
>> ...
>>
>> when remove driver, the golab variables defined by the macro
>> DEFINE_CORESIGHT_DEVLIST will be released, dict->nr_idx and
>> dict->fwnode_list are cleared to 0. The lifetime of the golab
>> variable has ended. So the buffer pointer is lost.
>>
>> Use the callback of devm_add_action_or_reset() to free memory.
>
> Thanks for the report. But please see below:
>
>>
>> Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names")
>> Signed-off-by: Junhao He <hejunhao3@...wei.com>
>> ---
>> drivers/hwtracing/coresight/coresight-core.c | 20 +++++++++++++++++++-
>> 1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-core.c
>> b/drivers/hwtracing/coresight/coresight-core.c
>> index 9fabe00a40d6..6849faad697d 100644
>> --- a/drivers/hwtracing/coresight/coresight-core.c
>> +++ b/drivers/hwtracing/coresight/coresight-core.c
>> @@ -1756,6 +1756,20 @@ bool coresight_loses_context_with_cpu(struct
>> device *dev)
>> }
>> EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);
>> +void coresight_release_dev_list(void *data)
>> +{
>> + struct coresight_dev_list *dict = data;
>> +
>> + mutex_lock(&coresight_mutex);
>> +
>> + if (dict->nr_idx) {
>> + kfree(dict->fwnode_list);
>> + dict->nr_idx = 0;
>> + }
>> +
>> + mutex_unlock(&coresight_mutex);
>> +}
>> +
>> /*
>> * coresight_alloc_device_name - Get an index for a given device in the
>> * device index list specific to a driver. An index is allocated for a
>> @@ -1766,12 +1780,16 @@
>> EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);
>> char *coresight_alloc_device_name(struct coresight_dev_list *dict,
>> struct device *dev)
>> {
>> - int idx;
>> + int idx, ret;
>> char *name = NULL;
>> struct fwnode_handle **list;
>> mutex_lock(&coresight_mutex);
>> + ret = devm_add_action_or_reset(dev, coresight_release_dev_list,
>> dict);
>> + if (ret)
>> + goto done;
>
> This looks wrong. The devlist should be only released on the "driver"
> unload, not on every device release. The list retains the fwnode to
> assign the same name for a device, if it is re-probed (e.g., due to
> -EPROBE_DEFER error).
The best way is to free it on module_unload and unfortunately we would
need to do it from all modules using the DEVLIST.
Suzuki
>
> Suzuki
>
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