patch "xhci: Fix NULL pointer dereference in xhci_clear_tt_buffer_complete()" added to usb-linus

patch "xhci: Fix NULL pointer dereference in xhci_clear_tt_buffer_complete()" added to usb-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    xhci: Fix NULL pointer dereference in xhci_clear_tt_buffer_complete()

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From cfbb8a84c2d2ef49bccacb511002bca4f6053555 Mon Sep 17 00:00:00 2001
From: Mathias Nyman <mathias.nyman@linux.intel.com>
Date: Fri, 4 Oct 2019 14:59:33 +0300
Subject: xhci: Fix NULL pointer dereference in xhci_clear_tt_buffer_complete()

udev stored in ep->hcpriv might be NULL if tt buffer is cleared
due to a halted control endpoint during device enumeration

xhci_clear_tt_buffer_complete is called by hub_tt_work() once it's
scheduled,  and by then usb core might have freed and allocated a
new udev for the next enumeration attempt.

Fixes: ef513be0a905 ("usb: xhci: Add Clear_TT_Buffer")
Cc: <stable@vger.kernel.org> # v5.3
Reported-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/1570190373-30684-9-git-send-email-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/host/xhci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 00f3804f7aa7..517ec3206f6e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -5238,8 +5238,16 @@ static void xhci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 	unsigned int ep_index;
 	unsigned long flags;
 
+	/*
+	 * udev might be NULL if tt buffer is cleared during a failed device
+	 * enumeration due to a halted control endpoint. Usb core might
+	 * have allocated a new udev for the next enumeration attempt.
+	 */
+
 	xhci = hcd_to_xhci(hcd);
 	udev = (struct usb_device *)ep->hcpriv;
+	if (!udev)
+		return;
 	slot_id = udev->slot_id;
 	ep_index = xhci_get_endpoint_index(&ep->desc);
 
-- 
2.23.0