From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by sourceware.org (Postfix) with ESMTPS id 120D43857001 for ; Wed, 27 Jul 2022 09:44:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 120D43857001 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 52666381BA; Wed, 27 Jul 2022 09:44:08 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 480FA13A8E; Wed, 27 Jul 2022 09:44:08 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id SK8uEegI4WJqUwAAMHmgww (envelope-from ); Wed, 27 Jul 2022 09:44:08 +0000 From: Fabian Vogt via Libc-alpha To: libc-alpha@sourceware.org Reply-To: Fabian Vogt Cc: schwab@suse.de Subject: [PATCH v2] nscd: Fix netlink cache invalidation if epoll is used [BZ #29415] Date: Wed, 27 Jul 2022 11:44:07 +0200 Message-ID: <5861791.lOV4Wx5bFT@linux-e202.suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Spam-Status: No, score=-8.2 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_NONE, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_SOFTFAIL, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Jul 2022 09:44:11 -0000 Processes cache network interface information such as whether IPv4 or IPv6 are enabled. This is only checked again if the "netlink timestamp" provided by nscd changed, which is triggered by netlink socket activity. However, in the epoll handler for the netlink socket, it was missed to assign the new timestamp to the nscd database. The handler for plain poll did that properly, copy that over. This bug caused that e.g. processes which started before network configuration got unusuable addresses from getaddrinfo, like IPv6 only even though only IPv4 is available: https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/1041 It's a bit hard to reproduce, so I verified this by checking the timestamp on calls to __check_pf manually. Without this patch it's stuck at 1, now it's increasing on network changes as expected. Signed-off-by: Fabian Vogt --- nscd/connections.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/nscd/connections.c b/nscd/connections.c index 61d1674eb4..531d2e83df 100644 --- a/nscd/connections.c +++ b/nscd/connections.c @@ -2284,7 +2284,8 @@ main_loop_epoll (int efd) sizeof (buf))) != -1) ; - __bump_nl_timestamp (); + dbs[hstdb].head->extra_data[NSCD_HST_IDX_CONF_TIMESTAMP] + = __bump_nl_timestamp (); } # endif else -- 2.36.1