linux-kernel - [PATCH] usb: host: xhci_debugfs: Fix a null pointer dereference in xhci_debugfs_create

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Date:   Sat,  4 May 2019 11:37:48 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     mathias.nyman@...el.com, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] usb: host: xhci_debugfs: Fix a null pointer dereference in xhci_debugfs_create_endpoint()

In xhci_debugfs_create_slot(), kzalloc() can fail and
dev->debugfs_private will be NULL.
In xhci_debugfs_create_endpoint(), dev->debugfs_private is used without
any null-pointer check, and can cause a null pointer dereference.

To fix this bug, a null-pointer check is added in
xhci_debugfs_create_endpoint().

This bug is found by a runtime fuzzing tool named FIZZER written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/usb/host/xhci-debugfs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/xhci-debugfs.c b/drivers/usb/host/xhci-debugfs.c
index cadc01336bf8..7ba6afc7ef23 100644
--- a/drivers/usb/host/xhci-debugfs.c
+++ b/drivers/usb/host/xhci-debugfs.c
@@ -440,6 +440,9 @@ void xhci_debugfs_create_endpoint(struct xhci_hcd *xhci,
 	struct xhci_ep_priv	*epriv;
 	struct xhci_slot_priv	*spriv = dev->debugfs_private;
 
+	if (!spriv)
+		return;
+
 	if (spriv->eps[ep_index])
 		return;
 
-- 
2.17.0