Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiang Liu Subject: [ 060/102] zram: avoid invalid memory access in zram_exit() Date: Thu, 8 Aug 2013 18:57:36 -0700 Message-Id: <20130809015024.373031068@linuxfoundation.org> In-Reply-To: <20130809015010.208118575@linuxfoundation.org> References: <20130809015010.208118575@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiang Liu commit 6030ea9b35971a4200062f010341ab832e878ac9 upstream. Memory for zram->disk object may have already been freed after returning from destroy_device(zram), then it's unsafe for zram_reset_device(zram) to access zram->disk again. We can't solve this bug by flipping the order of destroy_device(zram) and zram_reset_device(zram), that will cause deadlock issues to the zram sysfs handler. So fix it by holding an extra reference to zram->disk before calling destroy_device(zram). Signed-off-by: Jiang Liu Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zram/zram_drv.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -727,8 +727,10 @@ static void __exit zram_exit(void) for (i = 0; i < num_devices; i++) { zram = &zram_devices[i]; + get_disk(zram->disk); destroy_device(zram); zram_reset_device(zram); + put_disk(zram->disk); } unregister_blkdev(zram_major, "zram");