Re: Regression in 5.1.20: Reading long directory fails

[Chuck Lever]

> On Sep 11, 2019, at 1:40 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote:
> 
> On 11 Sep 2019, at 13:29, Chuck Lever wrote:
> 
>>> On Sep 11, 2019, at 1:26 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote:
>>> 
>>> 
>>> On 11 Sep 2019, at 12:39, Chuck Lever wrote:
>>> 
>>>>> On Sep 11, 2019, at 12:25 PM, Benjamin Coddington <bcodding@xxxxxxxxxx> wrote:
>>>>> 
>>> 
>>>>> Instead, I think we want to make sure the mic falls squarely into the tail
>>>>> every time.
>>>> 
>>>> I'm not clear how you could do that. The length of the page data is not
>>>> known to the client before it parses the reply. Are you suggesting that
>>>> gss_unwrap should do it somehow?
>>> 
>>> Is it too niave to always put the mic at the end of the tail?
>> 
>> The size of the page content is variable.
>> 
>> The only way the MIC will fall into the tail is if the page content is
>> exactly the largest expected size. When the page content is smaller than
>> that, the receive logic will place part or all of the MIC in ->pages.
> 
> Ok, right.  But what I meant is that xdr_buf_read_netobj() should be renamed
> and repurposed to be "move the mic from wherever it is to the end of
> xdr_buf's tail".
> 
> But now I see what you mean, and I also see that it is already trying to do
> that.. and we don't want to overlap the copy..
> 
> So, really, we need the tail to be larger than twice the mic.. less 1.  That
> means the fix is probably just increasing rslack for krb5i.

What's the justification for that particular maximum size? Are you sure the
page contents are not spilling into the tail?

--
Chuck Lever