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SubjectRe: [PATCH] dcache: Translating dentry into pathname without taking rename_lock
On 09/04/2013 03:43 PM, Al Viro wrote:
> On Wed, Sep 04, 2013 at 03:33:00PM -0400, Waiman Long wrote:
>
>> I have thought about that. But if a d_move() is going on, the string
>> in the buffer will be discarded as the sequence number will change.
>> So whether or not it have embedded null byte shouldn't matter. That
>> is why I didn't add code to do byte-by-byte copy at this first
>> patch. I can add code to do that if you think it is safer to do so.
> Sigh... Junk in the output is not an issue; reading from invalid address
> is, since you might not survive to the sequence number check. Again,
> if p is an address returned by kmalloc(size, ...), dereferencing p + offset
> is not safe unless offset is less than size.

Yeah, I understand that. As said in my reply to Linus, I will use
memchr() to see if there is null byte within the specified length. If
one is found, I will assume the string is not valid and return error to
the caller.

Longman


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