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Sun, 3 May 2026 22:12:47 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id W5EXOF/I92kabwAAD6G6ig (envelope-from ); Sun, 03 May 2026 22:12:47 +0000 From: Fernando Fernandez Mancera To: netdev@vger.kernel.org Cc: linux-kselftest@vger.kernel.org, horms@kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, idosch@nvidia.com, dsahern@kernel.org, Fernando Fernandez Mancera , =?UTF-8?q?=C5=81ukasz=20Stelmach?= Subject: [PATCH 1/2 net] ipv6: addrconf: fix temp address generation after prefix deprecation Date: Mon, 4 May 2026 00:11:40 +0200 Message-ID: <20260503221139.3742-3-fmancera@suse.de> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Spamd-Result: default: False [-3.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_SEVEN(0.00)[11]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid,suse.de:email]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Queue-Id: A1D4D6AF5C X-Spam-Flag: NO X-Spam-Score: -3.51 X-Spam-Level: When a router temporarily deprecates an IPv6 prefix (either by sending a Router Advertisement with Preferred Lifetime = 0 or by letting the lifetime expire) and later restores it, the kernel permanently loses its ability to generate temporary privacy addresses (RFC 8981) for that prefix. This happens because the address worker attempts to generate a replacement temporary address when the current one nears expiration. As the base prefix is deprecated already, the generation fails, burning the retry counter for temporary address generation of that prefix. When the router eventually restores the prefix, the temporary address becomes active again. However, once it naturally expires, the kernel sees the exhausted retry limit and permanently stops generating new privacy addresses. Fix this by verifying that the base prefix has sufficient preferred lifetime remaining before attempting to generate a new temporary address. This prevents the worker from burning through its retry counter during temporary network deprecation events like a router reboot. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Łukasz Stelmach Closes: https://lore.kernel.org/netdev/87340td30q.fsf%25steelman@post.pl/ Signed-off-by: Fernando Fernandez Mancera --- net/ipv6/addrconf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 5476b6536eb7..f6a3d9da3cb1 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -4654,9 +4654,11 @@ static void addrconf_verify_rtnl(struct net *net) !ifp->regen_count && ifp->ifpub) { /* This is a non-regenerated temporary addr. */ + unsigned long pub_age = (now - READ_ONCE(ifp->ifpub->tstamp)) / HZ; unsigned long regen_advance = ipv6_get_regen_advance(ifp->idev); - if (age + regen_advance >= ifp->prefered_lft) { + if (age + regen_advance >= ifp->prefered_lft && + pub_age + regen_advance < READ_ONCE(ifp->ifpub->prefered_lft)) { struct inet6_ifaddr *ifpub = ifp->ifpub; if (time_before(ifp->tstamp + ifp->prefered_lft * HZ, next)) next = ifp->tstamp + ifp->prefered_lft * HZ; -- 2.53.0