[PATCH v2] usb: tegra-xudc: check ep and ep->desc before deref

["Alexey V. Vissarionov" <gremlin@altlinux.org>]

Check ep before dereferencing it in trb_phys_to_virt() and ep->desc
before dereferencing it in tegra_xudc_req_done()

Found by ALT Linux Team (altlinux.org) and Linux Verification Center
(linuxtesting.org)

Fixes: 49db427232fe ("usb: gadget: Add UDC driver for tegra XUSB device mode controller")
Signed-off-by: Alexey V. Vissarionov <gremlin@altlinux.org>
---
 drivers/usb/gadget/udc/tegra-xudc.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/udc/tegra-xudc.c b/drivers/usb/gadget/udc/tegra-xudc.c
index c7fdbc55fb0b97ed..d61a0675e18f448f 100644
--- a/drivers/usb/gadget/udc/tegra-xudc.c
+++ b/drivers/usb/gadget/udc/tegra-xudc.c
@@ -2658,9 +2658,21 @@ static void tegra_xudc_handle_transfer_completion(struct tegra_xudc *xudc,
 	short_packet = (trb_read_cmpl_code(event) ==
 			TRB_CMPL_CODE_SHORT_PACKET);
 
+	/* trb_phys_to_virt() dereferences ep; check it here */
+	if (!ep) {
+		dev_err(xudc->dev, "unexpected NULL pointer: ep\n");
+		return;
+	}
+
 	trb = trb_phys_to_virt(ep, trb_read_data_ptr(event));
 	req = trb_to_request(ep, trb);
 
+	/* tegra_xudc_req_done() dereferences ep->desc; check it here */
+	if (!ep->desc) {
+		dev_err(xudc->dev, "unexpected NULL pointer: ep->desc\n");
+		return;
+	}
+
 	/*
 	 * TDs are complete on short packet or when the completed TRB is the
 	 * last TRB in the TD (the CHAIN bit is unset).
@@ -2678,7 +2690,7 @@ static void tegra_xudc_handle_transfer_completion(struct tegra_xudc *xudc,
 
 		tegra_xudc_req_done(ep, req, 0);
 
-		if (ep->desc && usb_endpoint_xfer_control(ep->desc))
+		if (usb_endpoint_xfer_control(ep->desc))
 			tegra_xudc_ep0_req_done(xudc);
 
 		/*
@@ -2694,8 +2706,7 @@ static void tegra_xudc_handle_transfer_completion(struct tegra_xudc *xudc,
 		dev_warn(xudc->dev, "transfer event on dequeued request\n");
 	}
 
-	if (ep->desc)
-		tegra_xudc_ep_kick_queue(ep);
+	tegra_xudc_ep_kick_queue(ep);
 }
 
 static void tegra_xudc_handle_transfer_event(struct tegra_xudc *xudc,



-- 
Alexey V. Vissarionov
gremlin ПРИ altlinux ТЧК org; +vii-cmiii-ccxxix-lxxix-xlii
GPG: 0D92F19E1C0DC36E27F61A29CD17E2B43D879005 @ hkp://keys.gnupg.net