staging: r8188eu: Fix potential memory leak or NULL dereference

In routine c2h_wk_callback(() following a kmalloc() call, the
error recovery is flawed. If the kmalloc() returns a pointer
that is not NULL, and the following c2h_evt_read() fails, the
code will leak that buffer. If the kmalloc() fails, a NULL
dereference will occur in the following code.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20210806213235.22349-1-Larry.Finger@lwfinger.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/r8188eu/core/rtw_cmd.c b/drivers/staging/r8188eu/core/rtw_cmd.c
index c3a9051..238ae79 100644 (file)
--- a/drivers/staging/r8188eu/core/rtw_cmd.c
+++ b/drivers/staging/r8188eu/core/rtw_cmd.c
@@ -1908,8 +1908,12 @@ static void c2h_wk_callback(struct work_struct *work)
                        c2h_evt = kmalloc(16, GFP_KERNEL);
                        if (c2h_evt) {
                                /* This C2H event is not read, read & clear now */
-                               if (c2h_evt_read(adapter, (u8 *)c2h_evt) != _SUCCESS)
+                               if (c2h_evt_read(adapter, (u8 *)c2h_evt) != _SUCCESS) {
+                                       kfree(c2h_evt);
                                        continue;
+                               }
+                       } else {
+                               return;
                        }
                }