smb/server: fix possible memory leak in smb2_read()

Memory leak occurs when ksmbd_vfs_read() fails.
Fix this by adding the missing kvfree().

Co-developed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: ZhangGuoDong <zhangguodong@kylinos.cn>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: ZhangGuoDong

fs/smb/server/smb2pdu.c

@@ -6824,6 +6824,7 @@ int smb2_read(struct ksmbd_work *work)
 
 	nbytes = ksmbd_vfs_read(work, fp, length, &offset, aux_payload_buf);
 	if (nbytes < 0) {
+		kvfree(aux_payload_buf);
 		err = nbytes;
 		goto out;
 	}