linux-kernel - [PATCH AUTOSEL 5.1 18/70] usb: xhci: Fix a potential null pointer dereference in xhci_debugfs_create

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Date:   Sat,  8 Jun 2019 07:38:57 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jia-Ju Bai <baijiaju1990@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>, linux-usb@...r.kernel.org
Subject: [PATCH AUTOSEL 5.1 18/70] usb: xhci: Fix a potential null pointer dereference in xhci_debugfs_create_endpoint()

From: Jia-Ju Bai <baijiaju1990@...il.com>

[ Upstream commit 5bce256f0b528624a34fe907db385133bb7be33e ]

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.

[subjet line change change, add potential -Mathais]
Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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;
 
-- 
2.20.1