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Subject: Re: [PATCH] ubi: fastmap: Don't produce the initial anchor PEB when
 fastmap is disabled
To:     Sascha Hauer <s.hauer@pengutronix.de>
CC:     <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <richard@nod.at>, <yi.zhang@huawei.com>
References: <20200601091134.3794265-1-chengzhihao1@huawei.com>
 <20200602092346.GK11869@pengutronix.de>
From:   Zhihao Cheng <chengzhihao1@huawei.com>
Message-ID: <e7a9e993-8878-60c8-49c4-9471421f6e11@huawei.com>
Date:   Tue, 2 Jun 2020 19:11:26 +0800
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?? 2020/6/2 17:23, Sascha Hauer д??:
> Hi,
>
> On Mon, Jun 01, 2020 at 05:11:34PM +0800, Zhihao Cheng wrote:
>> Following process triggers a memleak caused by forgetting to release the
>> initial anchor PEB (CONFIG_MTD_UBI_FASTMAP is disabled):
>> 1. attach -> __erase_worker -> produce the initial anchor PEB
>> 2. detach -> ubi_fastmap_close (Do nothing, it should have released the
>>     initial anchor PEB)
>>
>> Don't produce the initial anchor PEB in __erase_worker() when fastmap
>> is disabled.
>>
>> Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
>> Fixes: f9c34bb529975fe ("ubi: Fix producing anchor PEBs")
>> Reported-by: syzbot+d9aab50b1154e3d163f5@syzkaller.appspotmail.com
>> ---
>>   drivers/mtd/ubi/wl.c | 8 +++++++-
>>   1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
>> index 5146cce5fe32..5ebe1084a8e7 100644
>> --- a/drivers/mtd/ubi/wl.c
>> +++ b/drivers/mtd/ubi/wl.c
>> @@ -1079,13 +1079,19 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
>>   	if (!err) {
>>   		spin_lock(&ubi->wl_lock);
>>   
>> -		if (!ubi->fm_anchor && e->pnum < UBI_FM_MAX_START) {
>> +#ifdef CONFIG_MTD_UBI_FASTMAP
>> +		if (!ubi->fm_disabled && !ubi->fm_anchor &&
>> +		    e->pnum < UBI_FM_MAX_START) {
> Rather than introducing another #ifdef you could do a
>
> 		if (IS_ENABLED(CONFIG_MTD_UBI_FASTMAP) &&
> 		    !ubi->fm_disabled && !ubi->fm_anchor &&
> 		    e->pnum < UBI_FM_MAX_START)
>
> And I am not sure if the IS_ENABLED(CONFIG_MTD_UBI_FASTMAP) is necessary
> at all because we do a ubi->fm_disabled = 1 when fastmap is disabled.
>
> Regards,
>   Sascha
>
Agree.