Re: [PATCH 1/1] fix d_revalidate oopsen on NFS exports

[Tyler Hicks <tyhicks@canonical.com>]

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On 2011-11-29 19:25:01, Chris Dunlop wrote:
> Hi,
> 
> I haven't seen any response to this patch which fixes an Oops in
> d_revalidate. I hit this using NFS, but various other file
> systems look to be likewise vulnerable, hence the broadness of
> the patch. The sequence leading to the Oops is:
> 
> lookup_one_len() [fs/namei.c]
>    calls __lookup_hash() [fs/namei.c] with nd == NULL,
>       which can then call the file system specific d_revalidate(), passing in nd == NULL
>          which will then Oops if nd is used without checking

Hey Chris - Can you share what you were trying to do when you hit this?
Were you stacking eCryptfs on top of NFS? Another stacked filesystem on
top of NFS?

Do you *need* a stacked filesystem to work on top of NFS? If so, we'll
need to discuss a way forward. Al has previously shown a dislike of
eCryptfs passing around nameidata (for good reason), but that is what
NFS currently requires. I looked at doing this a few months back, but
never got to the implementation stage.

As David mentioned, Al's atomic open patches might solve all of this in
the future, but I don't know much about that patchset. Is there any
relevant info you could provide about those patches, Al?

Tyler

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