linux-kernel - Re: [PATCH] resource: Fix resource leak in get_free_mem

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Message-ID: <7e01507e-deb2-4acb-a2b7-530beb0d92dc@fujitsu.com>
Date: Tue, 4 Mar 2025 09:44:38 +0000
From: "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>
To: Mika Westerberg <mika.westerberg@...ux.intel.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew
 Morton <akpm@...ux-foundation.org>, Andy Shevchenko
	<andriy.shevchenko@...ux.intel.com>, "ilpo.jarvinen@...ux.intel.com"
	<ilpo.jarvinen@...ux.intel.com>, Bjorn Helgaas <bhelgaas@...gle.com>, Ying
 Huang <huang.ying.caritas@...il.com>, Dan Williams
	<dan.j.williams@...el.com>, Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	"linux-cxl@...r.kernel.org" <linux-cxl@...r.kernel.org>
Subject: Re: [PATCH] resource: Fix resource leak in get_free_mem_region()



On 04/03/2025 17:22, Mika Westerberg wrote:
> On Tue, Mar 04, 2025 at 12:34:15PM +0800, Li Zhijian wrote:
>> The leak is detected by the kernel memory leak detector (`kmemleak`)
>> following a `cxl create-region` failure:
>>
>>   cxl_acpi ACPI0017:00: decoder0.0: created region2
>>   cxl region2: HPA allocation error (-34) for size:0x0000000100000000 in CXL Window 0 [mem 0xa90000000-0x1a8fffffff flags 0x200]
>>   kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
>>
>>      __kmalloc_cache_noprof+0x28c/0x350
>>      get_free_mem_region+0x45/0x380
>>      alloc_free_mem_region+0x1d/0x30
>>      size_store+0x180/0x290 [cxl_core]
>>      kernfs_fop_write_iter+0x13f/0x1e0
>>      vfs_write+0x37c/0x540
>>      ksys_write+0x68/0xe0
>>      do_syscall_64+0x6e/0x190
>>      entry_SYSCALL_64_after_hwframe+0x76/0x7e
>>
>> Fixes: 14b80582c43e ("resource: Introduce alloc_free_mem_region()")
>> Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
>> ---
>>   kernel/resource.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/resource.c b/kernel/resource.c
>> index 12004452d999..aa0b1da143eb 100644
>> --- a/kernel/resource.c
>> +++ b/kernel/resource.c
>> @@ -2000,6 +2000,8 @@ get_free_mem_region(struct device *dev, struct resource *base,
>>   		devres_free(dr);
>>   	} else if (dev)
>>   		devm_release_action(dev, remove_free_mem_region, res);
>> +	else
>> +		free_resource(res);
> 
> It should use {} as per coding style:


The script/checkpatch.pl is happy with both of these 2 styles in practice.

Thanks
Zhijian

> 
> 	} else {
> 		free_resource(res);
> 	}
> 
> (probably should add that to the previous branch too).