Re: [PATCH] nfsd: fix leaked file lock with nfs exported overlayfs

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On Tue, Jul 17, 2018 at 5:24 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> On Fri, Jul 13, 2018 at 6:05 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>> On Fri, Jul 13, 2018 at 6:40 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>>> On Fri, 2018-07-13 at 17:22 +0300, Amir Goldstein wrote:
>>>> nfsd and lockd call vfs_lock_file() to lock/unlock the inode
>>>> returned by locks_inode(file).
>>>>
>>>> Many places in nfsd/lockd code use the inode returned by
>>>> file_inode(file) for lock manipulation. With Overlayfs, file_inode()
>>>> (the underlying inode) is not the same object as locks_inode() (the
>>>> overlay inode). This can result in "Leaked POSIX lock" messages
>>>> and eventually to a kernel crash as reported by Eddie Horng:
>>>> https://marc.info/?l=linux-unionfs&m=153086643202072&w=2
>>>>
>>>> Fix all the call sites in nfsd/lockd that should use locks_inode().
>>>> This is a correctness bug that manifested when overlayfs gained
>>>> NFS export support in v4.16.
>>>>
>>>> Reported-by: Eddie Horng <eddiehorng.tw@xxxxxxxxx>
>>>> Tested-by: Eddie Horng <eddiehorng.tw@xxxxxxxxx>
>>>> Cc: Jeff Layton <jlayton@xxxxxxxxxx>
>>>> Fixes: 8383f1748829 ("ovl: wire up NFS export operations")
>>>> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
>>>> ---
>>>>
>>>> Hi Bruce,
>>>>
>>>> For the purpose of locks, nfsd/lockd should look at locks_inode()
>>>> just like vfs lock functions.
>>>>
>>>> Hopefully, Miklos's work on stacked overlayfs file operations will
>>>> be merged soon and locks_inode() will become the same as file_inode(),
>>>> but we will still need this fix for stable kernels v4.16 through v4.18.
>
> Needs a Cc: stable@... tag then.
>
> Should I take this patch (based on the fact that it only affects
> overlayfs exports)?
>
> Or will you take it, Bruce?
>

Bruce? Jeff?

It's probably a good time for someone to put this patch in -next.

Should Miklos do it?

Thanks,
Amir.
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