Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753575AbbFHUzj (ORCPT ); Mon, 8 Jun 2015 16:55:39 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57856 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752747AbbFHUzd (ORCPT ); Mon, 8 Jun 2015 16:55:33 -0400 Date: Mon, 8 Jun 2015 13:55:32 -0700 From: Andrew Morton To: Sergey Senozhatsky Cc: Minchan Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky , Christoph Lameter , Pekka Enberg , Joonsoo Kim , David Rientjes Subject: Re: [PATCH] zsmalloc: fix a null pointer dereference in destroy_handle_cache() Message-Id: <20150608135532.ac913746b6394217e92a229a@linux-foundation.org> In-Reply-To: <1433502690-2524-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1433502690-2524-1-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1413 Lines: 44 On Fri, 5 Jun 2015 20:11:30 +0900 Sergey Senozhatsky 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. > ... > > --- 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/