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SubjectRe: [patch 1/3] NFS: fix potential NULL pointer dereference
On Thu, Apr 17, 2008 at 12:40 AM, Trond Myklebust
<trond.myklebust@fys.uio.no> wrote:
>
> 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
>
>

Thanks Trond, I'll remake it ASAP (but can't guarantie that it will be soon ;)


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