linux-kernel - Re: 3.12-rc3 memory leak in module memstick

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Date:	Tue, 01 Oct 2013 12:03:33 -0500
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	Alex Dubov <oakad@...oo.com>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: 3.12-rc3 memory leak in module memstick

On 10/01/2013 09:04 AM, Catalin Marinas wrote:
> On 30 September 2013 18:51, Larry Finger <Larry.Finger@...inger.net> wrote:
>> On 3.12-rc3, I detected a memory leak in module memstick. The kmemleak
>> results are listed below. The second output is after memstick was unloaded,
>> which shows that it is not a false positive from kmemleak.
>>
>> larrylap:~ # echo scan > /sys/kernel/debug/kmemleak
>> larrylap:~ # cat /sys/kernel/debug/kmemleak
>> unreferenced object 0xffff8800ae85c190 (size 16):
>>    comm "kworker/u4:3", pid 685, jiffies 4294916336 (age 2831.760s)
>>    hex dump (first 16 bytes):
>>      6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00  memstick0.......
>>    backtrace:
>>      [<ffffffff8146a0d1>] kmemleak_alloc+0x21/0x50
>>      [<ffffffff81160720>] __kmalloc_track_caller+0x160/0x2f0
>>      [<ffffffff81237b9b>] kvasprintf+0x5b/0x90
>>      [<ffffffff8122c0c1>] kobject_set_name_vargs+0x21/0x60
>>      [<ffffffff812e7f5c>] dev_set_name+0x3c/0x40
>>      [<ffffffffa02bf918>] memstick_check+0xb8/0x340 [memstick]
>>      [<ffffffff81069862>] process_one_work+0x1d2/0x670
>>      [<ffffffff8106a88a>] worker_thread+0x11a/0x370
>>      [<ffffffff81072ea6>] kthread+0xd6/0xe0
>>      [<ffffffff81478bbc>] ret_from_fork+0x7c/0xb0
>
> The leak is most likely coming from memstick_alloc_card() on the error
> path. Commit 0252c3b4f0 (memstick: struct device - replace bus_id with
> dev_name(), dev_set_name()) sets allocates the device name but 'card'
> is freed on the error path without freeing the name.

Thanks for the analysis. From that I am quite sure I can devise a patch.

Larry


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