linux-kernel - [PATCH] usb: cdns3: Don't use priv_dev uninitialized in cdns3_gadget_ep

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Date:   Wed,  3 Aug 2022 09:24:22 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Peter Chen <peter.chen@...nel.org>,
        Pawel Laszczak <pawell@...ence.com>,
        Roger Quadros <rogerq@...nel.org>,
        Aswath Govindraju <a-govindraju@...com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>,
        Andrey Strachuk <strochuk@...ras.ru>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] usb: cdns3: Don't use priv_dev uninitialized in cdns3_gadget_ep_enable()

Clang warns:

  drivers/usb/cdns3/cdns3-gadget.c:2290:11: error: variable 'priv_dev' is uninitialized when used here [-Werror,-Wuninitialized]
                  dev_dbg(priv_dev->dev, "usbss: invalid parameters\n");
                          ^~~~~~~~
  include/linux/dev_printk.h:155:18: note: expanded from macro 'dev_dbg'
          dynamic_dev_dbg(dev, dev_fmt(fmt), ##__VA_ARGS__)
                          ^~~
  include/linux/dynamic_debug.h:167:7: note: expanded from macro 'dynamic_dev_dbg'
                          dev, fmt, ##__VA_ARGS__)
                          ^~~
  include/linux/dynamic_debug.h:152:56: note: expanded from macro '_dynamic_func_call'
          __dynamic_func_call(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
                                                              ^~~~~~~~~~~
  include/linux/dynamic_debug.h:134:15: note: expanded from macro '__dynamic_func_call'
                  func(&id, ##__VA_ARGS__);               \
                              ^~~~~~~~~~~
  drivers/usb/cdns3/cdns3-gadget.c:2278:31: note: initialize the variable 'priv_dev' to silence this warning
          struct cdns3_device *priv_dev;
                                      ^
                                      = NULL
  1 error generated.

The priv_dev assignment was moved below the if statement to avoid
potentially dereferencing ep before it was checked but priv_dev is used
in the dev_dbg() call.

To fix this, move the priv_dev and comp_desc assignments back to their
original spot and hoist the ep check above those assignments with a call
to pr_debug() instead of dev_dbg().

Fixes: c3ffc9c4ca44 ("usb: cdns3: change place of 'priv_ep' assignment in cdns3_gadget_ep_dequeue(), cdns3_gadget_ep_enable()")
Link: https://github.com/ClangBuiltLinux/linux/issues/1680
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 drivers/usb/cdns3/cdns3-gadget.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 9ac7d0a8c5da..d21b69997e75 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -2284,16 +2284,20 @@ static int cdns3_gadget_ep_enable(struct usb_ep *ep,
 	int ret = 0;
 	int val;
 
+	if (!ep) {
+		pr_debug("usbss: ep not configured?\n");
+		return -EINVAL;
+	}
+
 	priv_ep = ep_to_cdns3_ep(ep);
+	priv_dev = priv_ep->cdns3_dev;
+	comp_desc = priv_ep->endpoint.comp_desc;
 
-	if (!ep || !desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
+	if (!desc || desc->bDescriptorType != USB_DT_ENDPOINT) {
 		dev_dbg(priv_dev->dev, "usbss: invalid parameters\n");
 		return -EINVAL;
 	}
 
-	comp_desc = priv_ep->endpoint.comp_desc;
-	priv_dev = priv_ep->cdns3_dev;
-
 	if (!desc->wMaxPacketSize) {
 		dev_err(priv_dev->dev, "usbss: missing wMaxPacketSize\n");
 		return -EINVAL;

base-commit: 8288c99fc263bcafc5df5fa8c278b2eb8106364e
-- 
2.37.1