Re: [2.6 patch] unexport uts_sem
From: Christoph Hellwig
Date: Wed May 21 2008 - 08:37:22 EST
On Tue, May 20, 2008 at 02:38:02PM -0400, Frank Ch. Eigler wrote:
> Sorry, I misspoke - this check is intended not to cross-check
> kernel-devel and the kernel itself, but the debuginfo or similar data
> that is given to describe target of a systemtap script. I guess for
> new enough kernels we'll just do that using buildid hash codes.
>
> By the way, there do appear to be a few suspect in-tree users of
> utsname() without uts_sem locking (usb/storage/usb.c
Just a debug printk. Note sure why this particular one needs to
print the version, but if it really wants to do it it should rather use
UTS_RELEASE.
> cifs/connect.c,
This one is quite fishy. Not sure what it needs the name for but the
kernel utsname is probably a bad choise. And yes, this one actually
is racy because the host name can change.
> char/random.c,
random.c is always built-in and utsname is called during the
single-threaded kernel initialization phase, so this is safe.
> fs/lockd/clntproc.c, ...).
Yes, this one is racy. Should probably be fixed by starting lockd
with CLONE_NEWUTS so that it never changed during it's lifetime.
It's probably not a good idea when it changes with outstanding lockd
request anyway.
> If these need to be fixed,
> then wouldn't uts_sem need to come back exported?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/