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Subject: Re: [PATCH v2] staging: erofs: keep corrupted fs from crashing kernel
 in erofs_namei()
To:     Dan Carpenter <dan.carpenter@oracle.com>
CC:     Gao Xiang <gaoxiang25@huawei.com>,
        Al Viro <viro@ZenIV.linux.org.uk>,
        "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
        <devel@driverdev.osuosl.org>, <linux-erofs@lists.ozlabs.org>,
        Chao Yu <chao@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        <stable@vger.kernel.org>, <weidu.du@huawei.com>,
        Fang Wei <fangwei1@huawei.com>, Miao Xie <miaoxie@huawei.com>
References: <20190201121631.15179-1-gaoxiang25@huawei.com>
 <a9381c0d-9857-4d03-710d-80006d426bbc@huawei.com>
 <20190215075757.GG2326@kadam>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <fb99bac2-2587-04fa-6ac2-f2e5f83af7c9@huawei.com>
Date:   Fri, 15 Feb 2019 17:32:33 +0800
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On 2019/2/15 15:57, Dan Carpenter wrote:
> On Fri, Feb 15, 2019 at 03:02:25PM +0800, Chao Yu wrote:
>> On 2019/2/1 20:16, Gao Xiang wrote:
>>> +	/*
>>> +	 * on-disk error, let's only BUG_ON in the debugging mode.
>>> +	 * otherwise, it will return 1 to just skip the invalid name
>>> +	 * and go on (in consideration of the lookup performance).
>>> +	 */
>>> +	DBG_BUGON(qd->name > qd->end);
>>
>> qd->name == qd->end is not allowed as well?
>>
>> So will it be better to return directly here?
>>
>> 	if (unlikely(qd->name >= qd->end)) {
>> 		DBG_BUGON(1);
>> 		return 1;
>> 	}
> 
> Please don't add likely/unlikely() annotations unless you have
> benchmarked it and it makes a difference.

Well, it only occur for corrupted image, since the image is readonly, so it
is really rare.

Thanks,

> 
> regards,
> dan carpenter
> 
> 
> 
> .
>