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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , Randy Dunlap , David Ahern , Ido Schimmel , Thomas Gleixner , Joel Granados , Petr Pavlu , Maoyi Xie , Gerd Rausch , Oleg Nesterov , Nikolay Aleksandrov , Chia-Yu Chang , Yung Chih Su , Wyatt Feng , Hannes Frederic Sowa , Flavio Leitner , "Paul E. McKenney" , Petr Mladek , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Sun, 01 Nov 2026 14:12:01 +0800, Jiayuan Chen wrote: > net.ipv6.mld_qrv only has a lower bound, but ipv6_mc_reset() stores it > into the u8 inet6_dev::mc_qrv, so 256 wraps to 0 and the first MLDv2 > Query received on the interface trips the WARN_ON() in mld_update_qrv(): > > WARN_ON(idev->mc_qrv == 0); > > WARNING: net/ipv6/mcast.c:1327 at mld_query_work+0x1fd2/0x2cb0, CPU#3: kworker/3:1/2688 > Workqueue: mld mld_query_work > RIP: 0010:mld_query_work+0x1fd2/0x2cb0 > Call Trace: > > process_one_work+0x93a/0x1b20 > worker_thread+0x6d0/0x11d0 > kthread+0x358/0x470 > ret_from_fork+0x5b3/0x820 > ret_from_fork_asm+0x1a/0x30 > > > Make the sysctl a u8 like mc_qrv and switch to proc_dou8vec_minmax(), > which rejects anything above 255, and document it. > > Fixes: 2f711939d2ea ("ipv6: add sysctl_mld_qrv to configure query robustness variable") > Cc: stable@vger.kernel.org > Reviewed-by: Fernando Fernandez Mancera > Signed-off-by: Jiayuan Chen Reviewed-by: Kuniyuki Iwashima