Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965373Ab2B1BOx (ORCPT ); Mon, 27 Feb 2012 20:14:53 -0500 Received: from mail-pz0-f46.google.com ([209.85.210.46]:57828 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965343Ab2B1BMi (ORCPT ); Mon, 27 Feb 2012 20:12:38 -0500 Authentication-Results: mr.google.com; spf=pass (google.com: domain of gregkh@linuxfoundation.org designates 10.68.231.7 as permitted sender) smtp.mail=gregkh@linuxfoundation.org MIME-Version: 1.0 Message-Id: <20120228010434.582975556@linuxfoundation.org> User-Agent: quilt/0.51-17.1 Date: Mon, 27 Feb 2012 17:05:28 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Huajun Li , Alan Stern , James Bottomley Subject: [ 59/72] [SCSI] scsi_scan: Fix Poison overwritten warning caused by using freed shost In-Reply-To: <20120228010511.GA8453@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4065 Lines: 107 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Huajun Li commit 267a6ad4aefaafbde607804c60945bcf97f91c1b upstream. In do_scan_async(), calling scsi_autopm_put_host(shost) may reference freed shost, and cause Posison overwitten warning. Yes, this case can happen, for example, an USB is disconnected just when do_scan_async() thread starts to run, then scsi_host_put() called in scsi_finish_async_scan() will lead to shost be freed(because the refcount of shost->shost_gendev decreases to 1 after USB disconnects), at this point, if references shost again, system will show following warning msg. To make scsi_autopm_put_host(shost) always reference a valid shost, put it just before scsi_host_put() in function scsi_finish_async_scan(). [ 299.281565] ============================================================================= [ 299.281634] BUG kmalloc-4096 (Tainted: G I ): Poison overwritten [ 299.281682] ----------------------------------------------------------------------------- [ 299.281684] [ 299.281752] INFO: 0xffff880056c305d0-0xffff880056c305d0. First byte 0x6a instead of 0x6b [ 299.281816] INFO: Allocated in scsi_host_alloc+0x4a/0x490 age=1688 cpu=1 pid=2004 [ 299.281870] __slab_alloc+0x617/0x6c1 [ 299.281901] __kmalloc+0x28c/0x2e0 [ 299.281931] scsi_host_alloc+0x4a/0x490 [ 299.281966] usb_stor_probe1+0x5b/0xc40 [usb_storage] [ 299.282010] storage_probe+0xa4/0xe0 [usb_storage] [ 299.282062] usb_probe_interface+0x172/0x330 [usbcore] [ 299.282105] driver_probe_device+0x257/0x3b0 [ 299.282138] __driver_attach+0x103/0x110 [ 299.282171] bus_for_each_dev+0x8e/0xe0 [ 299.282201] driver_attach+0x26/0x30 [ 299.282230] bus_add_driver+0x1c4/0x430 [ 299.282260] driver_register+0xb6/0x230 [ 299.282298] usb_register_driver+0xe5/0x270 [usbcore] [ 299.282337] 0xffffffffa04ab03d [ 299.282364] do_one_initcall+0x47/0x230 [ 299.282396] sys_init_module+0xa0f/0x1fe0 [ 299.282429] INFO: Freed in scsi_host_dev_release+0x18a/0x1d0 age=85 cpu=0 pid=2008 [ 299.282482] __slab_free+0x3c/0x2a1 [ 299.282510] kfree+0x296/0x310 [ 299.282536] scsi_host_dev_release+0x18a/0x1d0 [ 299.282574] device_release+0x74/0x100 [ 299.282606] kobject_release+0xc7/0x2a0 [ 299.282637] kobject_put+0x54/0xa0 [ 299.282668] put_device+0x27/0x40 [ 299.282694] scsi_host_put+0x1d/0x30 [ 299.282723] do_scan_async+0x1fc/0x2b0 [ 299.282753] kthread+0xdf/0xf0 [ 299.282782] kernel_thread_helper+0x4/0x10 [ 299.282817] INFO: Slab 0xffffea00015b0c00 objects=7 used=7 fp=0x (null) flags=0x100000000004080 [ 299.282882] INFO: Object 0xffff880056c30000 @offset=0 fp=0x (null) [ 299.282884] ... Signed-off-by: Huajun Li Acked-by: Alan Stern Signed-off-by: James Bottomley Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/scsi_scan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1815,6 +1815,7 @@ static void scsi_finish_async_scan(struc } spin_unlock(&async_scan_lock); + scsi_autopm_put_host(shost); scsi_host_put(shost); kfree(data); } @@ -1841,7 +1842,6 @@ static int do_scan_async(void *_data) do_scsi_scan_host(shost); scsi_finish_async_scan(data); - scsi_autopm_put_host(shost); return 0; } @@ -1869,7 +1869,7 @@ void scsi_scan_host(struct Scsi_Host *sh p = kthread_run(do_scan_async, data, "scsi_scan_%d", shost->host_no); if (IS_ERR(p)) do_scan_async(data); - /* scsi_autopm_put_host(shost) is called in do_scan_async() */ + /* scsi_autopm_put_host(shost) is called in scsi_finish_async_scan() */ } EXPORT_SYMBOL(scsi_scan_host); -- 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/