Messages in this thread | | | Subject | Re: [patch 1/3] NFS: fix potential NULL pointer dereference | From | Trond Myklebust <> | Date | Wed, 16 Apr 2008 16:40:28 -0400 |
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On Thu, 2008-04-17 at 00:19 +0400, Cyrill Gorcunov wrote: > Trond, I've just pointed the problem and its solution (which is seems > to be a bit ugly, according to the rest nfs coding principle). So if > you prefer to have such a check in 'walk_path' function - just say me > that. You choose :) Thanks for comments
> > So? The defensive coding principle is that you perform validity checks > > when the pointer is created. Otherwise, we could equally well have added > > the NULL deref check to nfs4_path_walk()...
No, your fix was correct, it was just incomplete.
The point I was making above was that defensive programming means that _all_ these validity/NULL pointer checks should really be done in nfs4_validate_mount_data and nfs_validate_mount_data. We shouldn't rely on checks in other parts of the code.
In fact, as an example: it looks to me as if the lack of a nfs_server.hostname, leads to a lack of nfs_client->cl_hostname, which will eventually cause an Oops if you 'cat /proc/fs/nfsfs/servers', or if you hit the printk in nfs_update_inode(), or various other dprintk()s.
Trond
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