Re: [PATCH] NFS: possible NULL pointer deref in nfs_sillyrename()

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Thu, 2006-08-17 at 00:22 +0200, Jesper Juhl wrote:
> The coverity checker spotted this as bug #1013.
> 
> If we get a NULL dentry->d_inode, then regardless of 
> NFS_PARANOIA or no NFS_PARANOIA, then if 
>    if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
> turns out to be false we'll end up dereferencing 
> that NULL d_inode in two places below.
> 
> And since the check for "(!dentry->d_inode)" even exists
> (although inside #ifdef NFS_PARANOIA) I take that to mean
> that this is a possibility. 

Sorry, but it isn't possible. See the checks in may_delete() (which is
called before ->unlink()) and nfs_rename().

IOW: Feel free to kill the NFS_PARANOIA crap. It looks like legacy code
from a debugging session about a decade or so ago.

Cheers,
  Trond

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