[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150609035717.GB3297@swordfish>
Date: Tue, 9 Jun 2015 12:57:17 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH] zsmalloc: fix a null pointer dereference in
destroy_handle_cache()
On (06/08/15 13:55), Andrew Morton wrote:
[..]
> > zs_destroy_pool()->destroy_handle_cache() invoked from
> > zs_create_pool() can pass a NULL ->handle_cachep pointer
> > to kmem_cache_destroy(), which will dereference it.
> >
>
> That's slightly lacking in details (under what circumstances will it
> crash) so I changed it to
>
> : If zs_create_pool()->create_handle_cache()->kmem_cache_create() fails,
> : zs_create_pool()->destroy_handle_cache() will dereference the NULL
> : pool->handle_cachep.
> :
> : Modify destroy_handle_cache() to avoid this.
>
Oh, sorry I first received "+ zsmalloc-fix-a-null-pointer-dereference-in-
destroy_handle_cache.patch added to -mm tree" message, so I replied
there. fetchmail works somewhat confusing over the last weeks.
> > ...
> >
> > --- a/mm/zsmalloc.c
> > +++ b/mm/zsmalloc.c
> > @@ -285,7 +285,8 @@ static int create_handle_cache(struct zs_pool *pool)
> >
> > static void destroy_handle_cache(struct zs_pool *pool)
> > {
> > - kmem_cache_destroy(pool->handle_cachep);
> > + if (pool->handle_cachep)
> > + kmem_cache_destroy(pool->handle_cachep);
> > }
> >
> > static unsigned long alloc_handle(struct zs_pool *pool)
>
> I'll apply this, but... from a bit of grepping I'm estimating that we
> have approximately 200 instances of
>
> if (foo)
> kmem_cache_destroy(foo);
>
> so obviously kmem_cache_destroy() should be doing the check.
Yes, I thought about this.
A naive grepping gave me 563 occurrences
git grep kmem_cache_destroy | wc -l
563
So I decided to hold this activity. Well, I think I can create this
patch bomb, it's trivial.
-ss
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists