Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754478Ab3GXOgh (ORCPT ); Wed, 24 Jul 2013 10:36:37 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45701 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751822Ab3GXOG2 (ORCPT ); Wed, 24 Jul 2013 10:06:28 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Greg Kroah-Hartman" , "Jiang Liu" , "Jiang Liu" Date: Wed, 24 Jul 2013 15:02:45 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [08/85] zram: avoid invalid memory access in zram_exit() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.101 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1524 Lines: 47 3.2.49-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- 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 @@ -846,9 +846,11 @@ static void __exit zram_exit(void) for (i = 0; i < zram_num_devices; i++) { zram = &zram_devices[i]; + get_disk(zram->disk); destroy_device(zram); if (zram->init_done) zram_reset_device(zram); + put_disk(zram->disk); } unregister_blkdev(zram_major, "zram"); -- 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/