Re: [PATCH] dcache: Translating dentry into pathname without takingrename_lock

[Waiman Long]

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/