src/tapset ChangeLog nfs.stp

[Mike Mason]

_get_sock_size() in the socket tapset does the same thing.  We should probably put an _iov_length() function in a generic auxiliary function tapset.  It's needed in a many places in filesystem tapsets.

Mike  

Wenji Huang wrote:
> Stone,
> 
>    Yes, It is more safe to duplicate this function with kread.
>    It returns same result as kernel iov_length. And in case of bad 
> pointer/nr_segs, there is kernel read fault error.
>    Please review it.
> 
>    function __iov_length:long(iov:long, nr_segs:long) %{ /*pure*/
>        unsigned long seg;
>        size_t ret = 0;
>        const struct iovec *iov = (const struct iovec *) (long) THIS->iov;
>        unsigned long nr_segs = (unsigned long) THIS->nr_segs;
> 
>        for (seg = 0; seg < nr_segs; seg++)
>                ret += kread(&(iov[seg].iov_len));
> 
>        THIS->__retvalue = (long) ret;
>        CATCH_DEREF_FAULT();
>    %}
> 
> Thanks,
> Wenji,
> 
> Stone, Joshua I wrote:
> 
>> wenji@sourceware.org wrote:
>>  
>>
>>> CVSROOT:    /cvs/systemtap
>>> Module name:    src
>>> Changes by:    wenji@sourceware.org    2007-08-20 08:12:00
>>>
>>> Modified files:
>>>     tapset         : ChangeLog nfs.stp
>>>
>>> Log message:
>>>     2007-08-20  Wenji Huang  <wenji.huang@oracle.com>
>>>     
>>>     * nfs.stp (nfs.fop.aio_read, nfs.fop.aio_write): Modify
>>>   
>> evaluating count.
>>  
>>
>>>     (__iov_length): New function.
>>>     (nfs.fop.sendfile, nfs.aop.set_page_dirty,
>>>   
>> nfs.aop.prepare_write,
>>  
>>
>>>     nfs.aop.release_page): Fix typo.
>>>   
>>
>> The new __iov_length() should not trust its parameters.  If it's ever
>> called with a bad pointer or bad nr_segs, the call to kernel
>> iov_length() will cause a system crash.
>>
>> The only safe way to handle this is to duplicate the functionality of
>> iov_length() with our own code that uses kread().  Thankfully it is a
>> small function in this case.
>>
>> Josh
>>
>>  
>>