staging: r8712: Fix memory leak in _r8712_init_xmit_priv()

In the above mentioned routine, memory is allocated in several places.
If the first succeeds and a later one fails, the routine will leak memory.
This patch fixes commit 2865d42c78a9 ("staging: r8712u: Add the new driver
to the mainline kernel"). A potential memory leak in
r8712_xmit_resource_alloc() is also addressed.

Fixes: 2865d42c78a9 ("staging: r8712u: Add the new driver to the mainline kernel")
Reported-by: [e-mail]
Closes: https://syzkaller.appspot.com/x/log.txt?x=11ac3fa0a80000
Cc: [e-mail]
Cc: Nam Cao <[e-mail]>
Signed-off-by: Larry Finger <[e-mail]>
Reviewed-by: Nam Cao <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/rtl8712/rtl871x_xmit.c

···
 #include "osdep_intf.h"
 #include "usb_ops.h"
 
+#include <linux/usb.h>
 #include <linux/ieee80211.h>
 
 static const u8 P802_1H_OUI[P80211_OUI_LEN] = {0x00, 0x00, 0xf8};
···
 	sint i;
 	struct xmit_buf *pxmitbuf;
 	struct xmit_frame *pxframe;
+	int j;
 
 	memset((unsigned char *)pxmitpriv, 0, sizeof(struct xmit_priv));
 	spin_lock_init(&pxmitpriv->lock);
···
 	_init_queue(&pxmitpriv->pending_xmitbuf_queue);
 	pxmitpriv->pallocated_xmitbuf =
 		kmalloc(NR_XMITBUFF * sizeof(struct xmit_buf) + 4, GFP_ATOMIC);
-	if (!pxmitpriv->pallocated_xmitbuf) {
-		kfree(pxmitpriv->pallocated_frame_buf);
-		pxmitpriv->pallocated_frame_buf = NULL;
-		return -ENOMEM;
-	}
+	if (!pxmitpriv->pallocated_xmitbuf)
+		goto clean_up_frame_buf;
 	pxmitpriv->pxmitbuf = pxmitpriv->pallocated_xmitbuf + 4 -
 			      ((addr_t)(pxmitpriv->pallocated_xmitbuf) & 3);
 	pxmitbuf = (struct xmit_buf *)pxmitpriv->pxmitbuf;
···
 		INIT_LIST_HEAD(&pxmitbuf->list);
 		pxmitbuf->pallocated_buf =
 			kmalloc(MAX_XMITBUF_SZ + XMITBUF_ALIGN_SZ, GFP_ATOMIC);
-		if (!pxmitbuf->pallocated_buf)
-			return -ENOMEM;
+		if (!pxmitbuf->pallocated_buf) {
+			j = 0;
+			goto clean_up_alloc_buf;
+		}
 		pxmitbuf->pbuf = pxmitbuf->pallocated_buf + XMITBUF_ALIGN_SZ -
 				 ((addr_t) (pxmitbuf->pallocated_buf) &
 				 (XMITBUF_ALIGN_SZ - 1));
-		if (r8712_xmit_resource_alloc(padapter, pxmitbuf))
-			return -ENOMEM;
+		if (r8712_xmit_resource_alloc(padapter, pxmitbuf)) {
+			j = 1;
+			goto clean_up_alloc_buf;
+		}
 		list_add_tail(&pxmitbuf->list,
 				 &(pxmitpriv->free_xmitbuf_queue.queue));
 		pxmitbuf++;
···
 	init_hwxmits(pxmitpriv->hwxmits, pxmitpriv->hwxmit_entry);
 	tasklet_setup(&pxmitpriv->xmit_tasklet, r8712_xmit_bh);
 	return 0;
+
+clean_up_alloc_buf:
+	if (j) {
+		/* failure happened in r8712_xmit_resource_alloc()
+		 * delete extra pxmitbuf->pallocated_buf
+		 */
+		kfree(pxmitbuf->pallocated_buf);
+	}
+	for (j = 0; j < i; j++) {
+		int k;
+
+		pxmitbuf--;			/* reset pointer */
+		kfree(pxmitbuf->pallocated_buf);
+		for (k = 0; k < 8; k++)		/* delete xmit urb's */
+			usb_free_urb(pxmitbuf->pxmit_urb[k]);
+	}
+	kfree(pxmitpriv->pallocated_xmitbuf);
+	pxmitpriv->pallocated_xmitbuf = NULL;
+clean_up_frame_buf:
+	kfree(pxmitpriv->pallocated_frame_buf);
+	pxmitpriv->pallocated_frame_buf = NULL;
+	return -ENOMEM;
 }
 
 void _free_xmit_priv(struct xmit_priv *pxmitpriv)

drivers/staging/rtl8712/xmit_linux.c

···
 	for (i = 0; i < 8; i++) {
 		pxmitbuf->pxmit_urb[i] = usb_alloc_urb(0, GFP_KERNEL);
 		if (!pxmitbuf->pxmit_urb[i]) {
+			int k;
+
+			for (k = i - 1; k >= 0; k--) {
+				/* handle allocation errors part way through loop */
+				usb_free_urb(pxmitbuf->pxmit_urb[k]);
+			}
 			netdev_err(padapter->pnetdev, "pxmitbuf->pxmit_urb[i] == NULL\n");
 			return -ENOMEM;
 		}