[PATCH 4.9 70/92] cw1200: Dont leak memory if krealloc failes

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Thumshirn <jthumshirn@xxxxxxx>

commit 9afdd6128c39f42398041bb2e017d8df0dcebcd1 upstream.

The call to krealloc() in wsm_buf_reserve() directly assigns the newly
returned memory to buf->begin. This is all fine except when krealloc()
failes we loose the ability to free the old memory pointed to by
buf->begin. If we just create a temporary variable to assign memory to
and assign the memory to it we can mitigate the memory leak.

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Signed-off-by: Amit Pundir <amit.pundir@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/wireless/st/cw1200/wsm.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/drivers/net/wireless/st/cw1200/wsm.c
+++ b/drivers/net/wireless/st/cw1200/wsm.c
@@ -1805,16 +1805,18 @@ static int wsm_buf_reserve(struct wsm_bu
 {
 	size_t pos = buf->data - buf->begin;
 	size_t size = pos + extra_size;
+	u8 *tmp;
 
 	size = round_up(size, FWLOAD_BLOCK_SIZE);
 
-	buf->begin = krealloc(buf->begin, size, GFP_KERNEL | GFP_DMA);
-	if (buf->begin) {
-		buf->data = &buf->begin[pos];
-		buf->end = &buf->begin[size];
-		return 0;
-	} else {
-		buf->end = buf->data = buf->begin;
+	tmp = krealloc(buf->begin, size, GFP_KERNEL | GFP_DMA);
+	if (!tmp) {
+		wsm_buf_deinit(buf);
 		return -ENOMEM;
 	}
+
+	buf->begin = tmp;
+	buf->data = &buf->begin[pos];
+	buf->end = &buf->begin[size];
+	return 0;
 }