From patchwork Tue May 15 02:49:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shuah X-Patchwork-Id: 10399791 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9B7AB601F7 for ; Tue, 15 May 2018 02:50:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 33CD327FB7 for ; Tue, 15 May 2018 02:50:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2637228068; Tue, 15 May 2018 02:50:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7D77C27FB7 for ; Tue, 15 May 2018 02:50:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752060AbeEOCu3 (ORCPT ); Mon, 14 May 2018 22:50:29 -0400 Received: from mailout.easymail.ca ([64.68.200.34]:55564 "EHLO mailout.easymail.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752044AbeEOCu3 (ORCPT ); Mon, 14 May 2018 22:50:29 -0400 Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id 4383421478; Tue, 15 May 2018 02:50:28 +0000 (UTC) Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (emo02-pco.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZPcwmlVrB0zv; Tue, 15 May 2018 02:50:28 +0000 (UTC) Received: from localhost.localdomain (c-24-9-64-241.hsd1.co.comcast.net [24.9.64.241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mailout.easymail.ca (Postfix) with ESMTPSA id F0E602109B; Tue, 15 May 2018 02:50:21 +0000 (UTC) From: "Shuah Khan (Samsung OSG)" To: valentina.manea.m@gmail.com, shuah@kernel.org, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] usbip: usbip_host: fix NULL-ptr deref and use-after-free errors Date: Mon, 14 May 2018 20:49:58 -0600 Message-Id: <20180515024958.3961-1-shuah@kernel.org> X-Mailer: git-send-email 2.14.1 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP usbip_host updates device status without holding lock from stub probe, disconnect and rebind code paths. When multiple requests to import a device are received, these unprotected code paths step all over each other and drive fails with NULL-ptr deref and use-after-free errors. The driver uses a table lock to protect the busid array for adding and deleting busids to the table. However, the probe, disconnect and rebind paths get the busid table entry and update the status without holding the busid table lock. Add a new finer grain lock to protect the busid entry. This new lock will be held to search and update the busid entry fields from get_busid_idx(), add_match_busid() and del_match_busid(). match_busid_show() does the same to access the busid entry fields. get_busid_priv() changed to return the pointer to the busid entry holding the busid lock. stub_probe(), stub_disconnect() and stub_device_rebind() call put_busid_priv() to release the busid lock before returning. This changes fixes the unprotected code paths eliminating the race conditions in updating the busid entries. Signed-off-by: Shuah Khan (Samsung OSG) --- drivers/usb/usbip/stub.h | 2 ++ drivers/usb/usbip/stub_dev.c | 33 +++++++++++++++++++++++---------- drivers/usb/usbip/stub_main.c | 40 +++++++++++++++++++++++++++++++++++----- 3 files changed, 60 insertions(+), 15 deletions(-) diff --git a/drivers/usb/usbip/stub.h b/drivers/usb/usbip/stub.h index 14a72357800a..35618ceb2791 100644 --- a/drivers/usb/usbip/stub.h +++ b/drivers/usb/usbip/stub.h @@ -73,6 +73,7 @@ struct bus_id_priv { struct stub_device *sdev; struct usb_device *udev; char shutdown_busid; + spinlock_t busid_lock; }; /* stub_priv is allocated from stub_priv_cache */ @@ -83,6 +84,7 @@ extern struct usb_device_driver stub_driver; /* stub_main.c */ struct bus_id_priv *get_busid_priv(const char *busid); +void put_busid_priv(struct bus_id_priv *bid); int del_match_busid(char *busid); void stub_device_cleanup_urbs(struct stub_device *sdev); diff --git a/drivers/usb/usbip/stub_dev.c b/drivers/usb/usbip/stub_dev.c index 9d0425113c4b..c0d6ff1baa72 100644 --- a/drivers/usb/usbip/stub_dev.c +++ b/drivers/usb/usbip/stub_dev.c @@ -300,7 +300,7 @@ static int stub_probe(struct usb_device *udev) struct stub_device *sdev = NULL; const char *udev_busid = dev_name(&udev->dev); struct bus_id_priv *busid_priv; - int rc; + int rc = 0; dev_dbg(&udev->dev, "Enter probe\n"); @@ -317,13 +317,15 @@ static int stub_probe(struct usb_device *udev) * other matched drivers by the driver core. * See driver_probe_device() in driver/base/dd.c */ - return -ENODEV; + rc = -ENODEV; + goto call_put_busid_priv; } if (udev->descriptor.bDeviceClass == USB_CLASS_HUB) { dev_dbg(&udev->dev, "%s is a usb hub device... skip!\n", udev_busid); - return -ENODEV; + rc = -ENODEV; + goto call_put_busid_priv; } if (!strcmp(udev->bus->bus_name, "vhci_hcd")) { @@ -331,13 +333,16 @@ static int stub_probe(struct usb_device *udev) "%s is attached on vhci_hcd... skip!\n", udev_busid); - return -ENODEV; + rc = -ENODEV; + goto call_put_busid_priv; } /* ok, this is my device */ sdev = stub_device_alloc(udev); - if (!sdev) - return -ENOMEM; + if (!sdev) { + rc = -ENOMEM; + goto call_put_busid_priv; + } dev_info(&udev->dev, "usbip-host: register new device (bus %u dev %u)\n", @@ -369,7 +374,9 @@ static int stub_probe(struct usb_device *udev) } busid_priv->status = STUB_BUSID_ALLOC; - return 0; + rc = 0; + goto call_put_busid_priv; + err_files: usb_hub_release_port(udev->parent, udev->portnum, (struct usb_dev_state *) udev); @@ -379,6 +386,9 @@ static int stub_probe(struct usb_device *udev) busid_priv->sdev = NULL; stub_device_free(sdev); + +call_put_busid_priv: + put_busid_priv(busid_priv); return rc; } @@ -417,7 +427,7 @@ static void stub_disconnect(struct usb_device *udev) /* get stub_device */ if (!sdev) { dev_err(&udev->dev, "could not get device"); - return; + goto call_put_busid_priv; } dev_set_drvdata(&udev->dev, NULL); @@ -432,12 +442,12 @@ static void stub_disconnect(struct usb_device *udev) (struct usb_dev_state *) udev); if (rc) { dev_dbg(&udev->dev, "unable to release port\n"); - return; + goto call_put_busid_priv; } /* If usb reset is called from event handler */ if (usbip_in_eh(current)) - return; + goto call_put_busid_priv; /* shutdown the current connection */ shutdown_busid(busid_priv); @@ -450,6 +460,9 @@ static void stub_disconnect(struct usb_device *udev) if (busid_priv->status == STUB_BUSID_ALLOC) busid_priv->status = STUB_BUSID_ADDED; + +call_put_busid_priv: + put_busid_priv(busid_priv); } #ifdef CONFIG_PM diff --git a/drivers/usb/usbip/stub_main.c b/drivers/usb/usbip/stub_main.c index 587b9bc10042..41c7b9de2a92 100644 --- a/drivers/usb/usbip/stub_main.c +++ b/drivers/usb/usbip/stub_main.c @@ -26,6 +26,8 @@ static spinlock_t busid_table_lock; static void init_busid_table(void) { + int i; + /* * This also sets the bus_table[i].status to * STUB_BUSID_OTHER, which is 0. @@ -33,6 +35,9 @@ static void init_busid_table(void) memset(busid_table, 0, sizeof(busid_table)); spin_lock_init(&busid_table_lock); + + for (i = 0; i < MAX_BUSID; i++) + spin_lock_init(&busid_table[i].busid_lock); } /* @@ -44,15 +49,20 @@ static int get_busid_idx(const char *busid) int i; int idx = -1; - for (i = 0; i < MAX_BUSID; i++) + for (i = 0; i < MAX_BUSID; i++) { + spin_lock(&busid_table[i].busid_lock); if (busid_table[i].name[0]) if (!strncmp(busid_table[i].name, busid, BUSID_SIZE)) { idx = i; + spin_unlock(&busid_table[i].busid_lock); break; } + spin_unlock(&busid_table[i].busid_lock); + } return idx; } +/* Returns holding busid_lock. Should call put_busid_priv() to unlock */ struct bus_id_priv *get_busid_priv(const char *busid) { int idx; @@ -60,13 +70,21 @@ struct bus_id_priv *get_busid_priv(const char *busid) spin_lock(&busid_table_lock); idx = get_busid_idx(busid); - if (idx >= 0) + if (idx >= 0) { bid = &(busid_table[idx]); + /* get busid_lock before returning */ + spin_lock(&bid->busid_lock); + } spin_unlock(&busid_table_lock); return bid; } +void put_busid_priv(struct bus_id_priv *bid) +{ + spin_unlock(&bid->busid_lock); +} + static int add_match_busid(char *busid) { int i; @@ -79,15 +97,19 @@ static int add_match_busid(char *busid) goto out; } - for (i = 0; i < MAX_BUSID; i++) + for (i = 0; i < MAX_BUSID; i++) { + spin_lock(&busid_table[i].busid_lock); if (!busid_table[i].name[0]) { strlcpy(busid_table[i].name, busid, BUSID_SIZE); if ((busid_table[i].status != STUB_BUSID_ALLOC) && (busid_table[i].status != STUB_BUSID_REMOV)) busid_table[i].status = STUB_BUSID_ADDED; ret = 0; + spin_unlock(&busid_table[i].busid_lock); break; } + spin_unlock(&busid_table[i].busid_lock); + } out: spin_unlock(&busid_table_lock); @@ -108,6 +130,8 @@ int del_match_busid(char *busid) /* found */ ret = 0; + spin_lock(&busid_table[idx].busid_lock); + if (busid_table[idx].status == STUB_BUSID_OTHER) memset(busid_table[idx].name, 0, BUSID_SIZE); @@ -115,6 +139,7 @@ int del_match_busid(char *busid) (busid_table[idx].status != STUB_BUSID_ADDED)) busid_table[idx].status = STUB_BUSID_REMOV; + spin_unlock(&busid_table[idx].busid_lock); out: spin_unlock(&busid_table_lock); @@ -127,9 +152,12 @@ static ssize_t match_busid_show(struct device_driver *drv, char *buf) char *out = buf; spin_lock(&busid_table_lock); - for (i = 0; i < MAX_BUSID; i++) + for (i = 0; i < MAX_BUSID; i++) { + spin_lock(&busid_table[i].busid_lock); if (busid_table[i].name[0]) out += sprintf(out, "%s ", busid_table[i].name); + spin_unlock(&busid_table[i].busid_lock); + } spin_unlock(&busid_table_lock); out += sprintf(out, "\n"); @@ -204,7 +232,7 @@ static void stub_device_rebind(void) } spin_unlock(&busid_table_lock); - /* now run rebind */ + /* now run rebind - no need to hold locks. driver files are removed */ for (i = 0; i < MAX_BUSID; i++) { if (busid_table[i].name[0] && busid_table[i].shutdown_busid) { @@ -234,6 +262,8 @@ static ssize_t rebind_store(struct device_driver *dev, const char *buf, /* mark the device for deletion so probe ignores it during rescan */ bid->status = STUB_BUSID_OTHER; + /* release the busid lock */ + put_busid_priv(bid); ret = do_rebind((char *) buf, bid); if (ret < 0)