ksmbd: prevent memory leak on error return

When allocated memory for 'new' failed,just return
will cause memory leak of 'ar'.

Fixes: 1819a90 ("ksmbd: reorganize ksmbd_iov_pin_rsp()")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/r/202311031837.H3yo7JVl-lkp@intel.com/
Signed-off-by: Zongmin Zhou<zhouzongmin@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/ksmbd_work.c

@@ -106,7 +106,7 @@ static inline void __ksmbd_iov_pin(struct ksmbd_work *work, void *ib,
 static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
 			       void *aux_buf, unsigned int aux_size)
 {
-	struct aux_read *ar;
+	struct aux_read *ar = NULL;
 	int need_iov_cnt = 1;
 
 	if (aux_size) {
@@ -123,8 +123,11 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
 		new = krealloc(work->iov,
 			       sizeof(struct kvec) * work->iov_alloc_cnt,
 			       GFP_KERNEL | __GFP_ZERO);
-		if (!new)
+		if (!new) {
+			kfree(ar);
+			work->iov_alloc_cnt -= 4;
 			return -ENOMEM;
+		}
 		work->iov = new;
 	}