Messages in this thread | | | Date | Thu, 17 Aug 2023 15:46:29 +0100 | Subject | Re: [PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list | From | Suzuki K Poulose <> |
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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 */
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