Re: [Regression] "SUNRPC: Add "@len" parameter to gss_unwrap()" breaks NFS Kerberos on upstream stable 5.4.y

[Chuck Lever]

> On Jul 15, 2020, at 11:08 AM, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
> 
>> On Jul 15, 2020, at 23:02, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>> 
>>> On Jul 15, 2020, at 10:48 AM, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> wrote:
>>> 
>>> Hi,
>>> 
>>> Multiple users reported NFS causes NULL pointer dereference [1] on Ubuntu, due to commit "SUNRPC: Add "@len" parameter to gss_unwrap()" and commit "SUNRPC: Fix GSS privacy computation of auth->au_ralign".
>>> 
>>> The same issue happens on upstream stable 5.4.y branch.
>>> The mainline kernel doesn't have this issue though.
>>> 
>>> Should we revert them? Or is there any missing commits need to be backported to v5.4?
>>> 
>>> [1] https://bugs.launchpad.net/bugs/1886277
>>> 
>>> Kai-Heng
>> 
>> 31c9590ae468 ("SUNRPC: Add "@len" parameter to gss_unwrap()") is a refactoring
>> change. It shouldn't have introduced any behavior difference. But in theory,
>> practice and theory should be the same...
>> 
>> Check if 0a8e7b7d0846 ("SUNRPC: Revert 241b1f419f0e ("SUNRPC: Remove xdr_buf_trim()")")
>> is also applied to 5.4.0-40-generic.
> 
> Yes, it's included. The commit is part of upstream stable 5.4.
> 
>> 
>> It would help to know if v5.5 stable is working for you. I haven't had any
>> problems with it.
> 
> I'll ask users to test it out. 
> Thanks for you quick reply!

Another thought: Please ask what encryption type is in use. The
kerberos_v1 enctypes might exercise a code path I wasn't able to
test.


--
Chuck Lever