Re: [RFC][PATCH] sunrpc: fix oops in rpc_create() when the mount namespace is unshared

[Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>]

Eric W. Biederman wrote:
> Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org> writes:
> 
>> On a system with nfs mounts, if a task unshares its mount namespace,
>> a oops can occur when the system is rebooted if the task is the last
>> to unreference the nfs mount. It will try to create a rpc request
>> using utsname() which has been invalidated by free_nsproxy().
>>
>> The patch fixes the issue by using the global init_utsname() but at
>> the same time, it breaks the capability of identifying rpc clients
>> per uts namespace.
>>
>> Any better suggestions ?
> 
> Can we push utsname into rpc_create_args and push the access
> of utsname up the food chain?

struct rpc_create_args seems to be used only as a stack argument 
for rpc_create() it's not kept in any nfs or sunrpc objects.
 
> My gut feeling says we should capture the utsname or the
> uts_ns when we mount the nfs filesystem so we stay in sync
> for the life of the mount.

I see. It make sense but, looking at the code, the nfs and sunrpc 
will need some heavy changes ...

Thanks,

C.
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