linux-kernel - [PATCH v4 2/2] usb: gadget: clear related members when goto fail

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Message-Id: <20211231172138.7993-3-hbh25y@gmail.com>
Date:   Sat,  1 Jan 2022 01:21:38 +0800
From:   Hangyu Hua <hbh25y@...il.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org, axboe@...nel.dk,
        dan.carpenter@...cle.com, jj251510319013@...il.com,
        stern@...land.harvard.edu
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hangyu Hua <hbh25y@...il.com>
Subject: [PATCH v4 2/2] usb: gadget: clear related members when goto fail

dev->config and dev->hs_config and dev->dev need to be cleaned if
dev_config fails to avoid UAF.

Signed-off-by: Hangyu Hua <hbh25y@...il.com>
---
 drivers/usb/gadget/legacy/inode.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index eaad03c0252f..25c8809e0a38 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -1875,8 +1875,8 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 
 	value = usb_gadget_probe_driver(&gadgetfs_driver);
 	if (value != 0) {
-		kfree (dev->buf);
-		dev->buf = NULL;
+		spin_lock_irq(&dev->lock);
+		goto fail;
 	} else {
 		/* at this point "good" hardware has for the first time
 		 * let the USB the host see us.  alternatively, if users
@@ -1893,6 +1893,9 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
 	return value;
 
 fail:
+	dev->config = NULL;
+	dev->hs_config = NULL;
+	dev->dev = NULL;
 	spin_unlock_irq (&dev->lock);
 	pr_debug ("%s: %s fail %zd, %p\n", shortname, __func__, value, dev);
 	kfree (dev->buf);
-- 
2.25.1