smb: client: Add check for next_buffer in receive_encrypted_standard()

Add check for the return value of cifs_buf_get() and cifs_small_buf_get()
in receive_encrypted_standard() to prevent null pointer dereference.

Fixes: eec04ea ("smb: client: fix OOB in receive_encrypted_standard()")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/smb2ops.c

@@ -4965,6 +4965,10 @@ receive_encrypted_standard(struct TCP_Server_Info *server,
 			next_buffer = (char *)cifs_buf_get();
 		else
 			next_buffer = (char *)cifs_small_buf_get();
+		if (!next_buffer) {
+			cifs_server_dbg(VFS, "No memory for (large) SMB response\n");
+			return -1;
+		}
 		memcpy(next_buffer, buf + next_cmd, pdu_length - next_cmd);
 	}