lkml.org 
[lkml]   [2023]   [Aug]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list
From
On 17/08/2023 15:31, James Clark 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.
>>
>> Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names")
>> Signed-off-by: Junhao He <hejunhao3@huawei.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;
>> +
>
> Hi Junhao,
>
> Changing the list allocator to a devm one fixes the issue without having
> to add the callback:
>
> - list = krealloc_array(dict->fwnode_list,
> + list = devm_krealloc_array(dev, dict->fwnode_list,

Thats problematic. Please note that the list is "per module/driver" not
per device. So, you cannot tie it to a single device. Please see my
response in the thread.

Suzuki


>
> The callback stands out a bit and would make someone reading it wonder
> why only that one is done that way but all other allocations in
> Coresight avoid it.
>
> The nr_idx variable doesn't need to be zeroed because its backed by a
> static variable and is zeroed when the module is reloaded as far as I
> can see.
>
> Thanks
> James
>
>> idx = coresight_search_device_idx(dict, dev_fwnode(dev));
>> if (idx < 0) {
>> /* Make space for the new entry */

\
 
 \ /
  Last update: 2023-08-17 16:48    [W:0.073 / U:0.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site