Messages in this thread |  | | Date | Tue, 9 Jun 2015 12:57:17 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH] zsmalloc: fix a null pointer dereference in destroy_handle_cache() |
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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
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