usbnet: fix memory leak in error case

usbnet_write_cmd_async() mixed up which buffers
need to be freed in which error case.

v2: add Fixes tag
v3: fix uninitialized buf pointer

Fixes: 877bd862f32b8 ("usbnet: introduce usbnet 3 command helpers")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20220705125351.17309-1-oneukum@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index e2135ab..78a9275 100644 (file)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -2137,7 +2137,7 @@ static void usbnet_async_cmd_cb(struct urb *urb)
 int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
                           u16 value, u16 index, const void *data, u16 size)
 {
-       struct usb_ctrlrequest *req = NULL;
+       struct usb_ctrlrequest *req;
        struct urb *urb;
        int err = -ENOMEM;
        void *buf = NULL;
@@ -2155,7 +2155,7 @@ int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
                if (!buf) {
                        netdev_err(dev->net, "Error allocating buffer"
                                   " in %s!\n", __func__);
-                       goto fail_free;
+                       goto fail_free_urb;
                }
        }
 
@@ -2179,14 +2179,21 @@ int usbnet_write_cmd_async(struct usbnet *dev, u8 cmd, u8 reqtype,
        if (err < 0) {
                netdev_err(dev->net, "Error submitting the control"
                           " message: status=%d\n", err);
-               goto fail_free;
+               goto fail_free_all;
        }
        return 0;
 
+fail_free_all:
+       kfree(req);
 fail_free_buf:
        kfree(buf);
-fail_free:
-       kfree(req);
+       /*
+        * avoid a double free
+        * needed because the flag can be set only
+        * after filling the URB
+        */
+       urb->transfer_flags = 0;
+fail_free_urb:
        usb_free_urb(urb);
 fail:
        return err;