Messages in this thread | | | Date | Sat, 15 Dec 2007 01:13:31 +0100 | From | Adrian Bunk <> | Subject | Re: [PATCH] tmpfs: restore missing clear_highpage |
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On Wed, Dec 12, 2007 at 05:01:51AM +0000, Hugh Dickins wrote: > On Tue, 11 Dec 2007, Chuck Ebbert wrote: > > On 11/28/2007 01:55 PM, Hugh Dickins wrote: > > > tmpfs was misconverted to __GFP_ZERO in 2.6.11. There's an unusual case in > > > which shmem_getpage receives the page from its caller instead of allocating. > > > We must cover this case by clear_highpage before SetPageUptodate, as before. > > > > > > Signed-off-by: Hugh Dickins <hugh@veritas.com> > > > --- > > > > What are the symptoms of the bug this fixes? > > I've not seen it in practice, just noticed it while working on that > area in the code. What's the polite way of describing these things > in public? It's a vulnerability which might allow an attacker to > access data from inside the kernel which should have been zeroed - > in very limited circumstances I'd prefer not to have to devise and > announce. > > It would also be wrong data, so could for example crash any program > rightly relying on uninitialized static data to be zeroed - in the > unlikely event that its data was coming via this route (in most setups > it never can do, perhaps I'd conclude that's true of all setups). It > has escaped notice for nearly three years, so it's not a commonplace. > > Further discussion offline if you like!
Can we get or is there already a CVE number?
> Hugh
cu Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed
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