[PATCH v3] staging: rtl8712: fix potential memory leak in _r8712_init_xmit_priv()

[xkernel . wang]

From: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>

In _r8712_init_xmit_priv(), if `pxmitbuf->pallocated_buf` is allocated in
failure or `r8712_xmit_resource_alloc(padapter, pxmitbuf)` fails, then it
just returns -ENOMEM but not releases the previous allocated resources,
which can lead to various memory leaks.

To fix them, this patch unifies the error handler in the above function.
Note that if `r8712_xmit_resource_alloc(padapter, pxmitbuf)` fails, we
first call `kfree(pxmitbuf->pallocated_buf);` before goto the error
section so that we do not need to concern the failed item.

As there is no proper device to test with, no runtime testing was
performed.

Signed-off-by: Xiaoke Wang <xkernel.wang@xxxxxxxxxxx>
---
ChangeLog:
v1->v2 update the description.
v2->v3 update the description.
 drivers/staging/rtl8712/rtl871x_xmit.c | 27 ++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/rtl8712/rtl871x_xmit.c b/drivers/staging/rtl8712/rtl871x_xmit.c
index 090345b..dcf3f76 100644
--- a/drivers/staging/rtl8712/rtl871x_xmit.c
+++ b/drivers/staging/rtl8712/rtl871x_xmit.c
@@ -117,11 +117,8 @@ int _r8712_init_xmit_priv(struct xmit_priv *pxmitpriv,
 	_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 free_frame_buf;
 	pxmitpriv->pxmitbuf = pxmitpriv->pallocated_xmitbuf + 4 -
 			      ((addr_t)(pxmitpriv->pallocated_xmitbuf) & 3);
 	pxmitbuf = (struct xmit_buf *)pxmitpriv->pxmitbuf;
@@ -130,12 +127,14 @@ int _r8712_init_xmit_priv(struct xmit_priv *pxmitpriv,
 		pxmitbuf->pallocated_buf =
 			kmalloc(MAX_XMITBUF_SZ + XMITBUF_ALIGN_SZ, GFP_ATOMIC);
 		if (!pxmitbuf->pallocated_buf)
-			return -ENOMEM;
+			goto free_xmitbuf;
 		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)) {
+			kfree(pxmitbuf->pallocated_buf);
+			goto free_xmitbuf;
+		}
 		list_add_tail(&pxmitbuf->list,
 				 &(pxmitpriv->free_xmitbuf_queue.queue));
 		pxmitbuf++;
@@ -146,6 +145,18 @@ int _r8712_init_xmit_priv(struct xmit_priv *pxmitpriv,
 	init_hwxmits(pxmitpriv->hwxmits, pxmitpriv->hwxmit_entry);
 	tasklet_setup(&pxmitpriv->xmit_tasklet, r8712_xmit_bh);
 	return 0;
+
+free_xmitbuf:
+	pxmitbuf = (struct xmit_buf *)pxmitpriv->pxmitbuf;
+	while (i--) {
+		r8712_xmit_resource_free(padapter, pxmitbuf);
+		kfree(pxmitbuf->pallocated_buf);
+		pxmitbuf++;
+	}
+	kfree(pxmitpriv->pallocated_xmitbuf);
+free_frame_buf:
+	kfree(pxmitpriv->pallocated_frame_buf);
+	return -ENOMEM;
 }
 
 void _free_xmit_priv(struct xmit_priv *pxmitpriv)
--