From mboxrd@z Thu Jan 1 00:00:00 1970 From: colyli@suse.de Subject: [PATCH 05/17] bcache: fix use-after-free in register_bcache() Date: Fri, 24 Jan 2020 01:01:30 +0800 Message-ID: <20200123170142.98974-6-colyli@suse.de> References: <20200123170142.98974-1-colyli@suse.de> Return-path: Received: from mx2.suse.de ([195.135.220.15]:51432 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729641AbgAWRCO (ORCPT ); Thu, 23 Jan 2020 12:02:14 -0500 In-Reply-To: <20200123170142.98974-1-colyli@suse.de> Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: axboe@kernel.dk Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org, Coly Li , Christoph Hellwig From: Coly Li The patch "bcache: rework error unwinding in register_bcache" introduces a use-after-free regression in register_bcache(). Here are current code, 2510 out_free_path: 2511 kfree(path); 2512 out_module_put: 2513 module_put(THIS_MODULE); 2514 out: 2515 pr_info("error %s: %s", path, err); 2516 return ret; If some error happens and the above code path is executed, at line 2511 path is released, but referenced at line 2515. Then KASAN reports a use- after-free error message. This patch changes line 2515 in the following way to fix the problem, 2515 pr_info("error %s: %s", path?path:"", err); Signed-off-by: Coly Li Cc: Christoph Hellwig --- drivers/md/bcache/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index ee7c87f38d0d..fad9c6cbee5e 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -2477,10 +2477,11 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, kfree(sb); out_free_path: kfree(path); + path = NULL; out_module_put: module_put(THIS_MODULE); out: - pr_info("error %s: %s", path, err); + pr_info("error %s: %s", path?path:"", err); return ret; } -- 2.16.4