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From: Shuah Khan <skhan@linuxfoundation.org>
To: valentina.manea.m@gmail.com, shuah@kernel.org,
	gregkh@linuxfoundation.org
Cc: Shuah Khan <skhan@linuxfoundation.org>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com,
	stable@vger.kernel.org
Subject: [PATCH 3/4] usbip: vudc synchronize sysfs code paths
Date: Mon, 29 Mar 2021 19:36:50 -0600
Message-ID: <caabcf3fc87bdae970509b5ff32d05bb7ce2fb15.1616807117.git.skhan@linuxfoundation.org> (raw)
In-Reply-To: <cover.1616807117.git.skhan@linuxfoundation.org>

Fuzzing uncovered race condition between sysfs code paths in usbip
drivers. Device connect/disconnect code paths initiated through
sysfs interface are prone to races if disconnect happens during
connect and vice versa.

Use sysfs_lock to protect sysfs paths in vudc.

Reported-and-tested-by: syzbot+a93fba6d384346a761e3@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
 drivers/usb/usbip/vudc_dev.c   | 1 +
 drivers/usb/usbip/vudc_sysfs.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c
index c8eeabdd9b56..2bc428f2e261 100644
--- a/drivers/usb/usbip/vudc_dev.c
+++ b/drivers/usb/usbip/vudc_dev.c
@@ -572,6 +572,7 @@ static int init_vudc_hw(struct vudc *udc)
 	init_waitqueue_head(&udc->tx_waitq);
 
 	spin_lock_init(&ud->lock);
+	mutex_init(&ud->sysfs_lock);
 	ud->status = SDEV_ST_AVAILABLE;
 	ud->side = USBIP_VUDC;
 
diff --git a/drivers/usb/usbip/vudc_sysfs.c b/drivers/usb/usbip/vudc_sysfs.c
index 7383a543c6d1..f7633ee655a1 100644
--- a/drivers/usb/usbip/vudc_sysfs.c
+++ b/drivers/usb/usbip/vudc_sysfs.c
@@ -112,6 +112,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 		dev_err(dev, "no device");
 		return -ENODEV;
 	}
+	mutex_lock(&udc->ud.sysfs_lock);
 	spin_lock_irqsave(&udc->lock, flags);
 	/* Don't export what we don't have */
 	if (!udc->driver || !udc->pullup) {
@@ -187,6 +188,8 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 
 		wake_up_process(udc->ud.tcp_rx);
 		wake_up_process(udc->ud.tcp_tx);
+
+		mutex_unlock(&udc->ud.sysfs_lock);
 		return count;
 
 	} else {
@@ -207,6 +210,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 	}
 
 	spin_unlock_irqrestore(&udc->lock, flags);
+	mutex_unlock(&udc->ud.sysfs_lock);
 
 	return count;
 
@@ -216,6 +220,7 @@ static ssize_t usbip_sockfd_store(struct device *dev,
 	spin_unlock_irq(&udc->ud.lock);
 unlock:
 	spin_unlock_irqrestore(&udc->lock, flags);
+	mutex_unlock(&udc->ud.sysfs_lock);
 
 	return ret;
 }
-- 
2.27.0


  parent reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30  1:36 [PATCH 0/4] usbip " Shuah Khan
2021-03-30  1:36 ` [PATCH 1/4] usbip: add sysfs_lock to " Shuah Khan
2021-03-30  1:36 ` [PATCH 2/4] usbip: stub-dev " Shuah Khan
2021-03-30  1:36 ` Shuah Khan [this message]
2021-03-30  1:36 ` [PATCH 4/4] usbip: synchronize event handler with " Shuah Khan

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