From: Fernando Fernandez Mancera <fmancera@suse.de>
To: Jiayuan Chen <jiayuan.chen@linux.dev>, netdev@vger.kernel.org
Cc: stable@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@kernel.org>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>, David Ahern <dsahern@kernel.org>,
Ido Schimmel <idosch@nvidia.com>,
Kuniyuki Iwashima <kuniyu@google.com>,
Joel Granados <joel.granados@kernel.org>,
Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>,
Wyatt Feng <bronzed_45_vested@icloud.com>,
Yung Chih Su <yuuchihsu@gmail.com>,
Hannes Frederic Sowa <hannes@stressinduktion.org>,
Flavio Leitner <fbl@redhat.com>, Petr Mladek <pmladek@suse.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 4/5] ipv4: restrict igmp_qrv to 255
Date: Fri, 23 Oct 2026 16:14:33 +0200 [thread overview]
Message-ID: <68ac72a8-7642-4d10-ae61-8fc547b9c40a@suse.de> (raw)
In-Reply-To: <20261023091419.167088-5-jiayuan.chen@linux.dev>
On 10/23/26 11:13 AM, Jiayuan Chen wrote:
> net.ipv4.igmp_qrv only has a lower bound, but ip_mc_reset() stores it
> into the u8 in_device::mr_qrv, and the IGMPv3 retransmit counters filled
> from it (crcount, sf_crcount) are u8 as well. Anything above 255
> silently wraps. With 256, mr_qrv becomes 0, every
> "in_dev->mr_qrv ?: sysctl_igmp_qrv" falls back to 256, which truncates
> to 0 again in crcount, and igmpv3_send_cr() never puts the state change
> records for the group into a report. The older version querier present
> timeout (mr_qrv * mr_qi + mr_qri) also collapses to just mr_qri.
>
> Unlike MLD there is no WARN_ON() here, the reports just go missing.
>
> Cap the sysctl at U8_MAX, the largest value mr_qrv can actually hold.
>
> Fixes: a9fe8e29945d ("ipv4: implement igmp_qrv sysctl to tune igmp robustness variable")
> Cc: stable@vger.kernel.org
> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Thanks!
next prev parent reply other threads:[~2026-10-23 14:15 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-23 9:13 [PATCH net 0/5] net: fix misc signed overflows caused by bad sysctl values Jiayuan Chen
2026-10-23 9:13 ` [PATCH net 1/5] ipv6: restrict gc_elasticity to 31 Jiayuan Chen
2026-10-23 13:31 ` Fernando Fernandez Mancera
2026-10-23 9:13 ` [PATCH net 2/5] ipv4: fix shift-out-of-bounds in ip_rt_send_redirect() Jiayuan Chen
2026-10-23 14:11 ` Fernando Fernandez Mancera
2026-10-23 14:38 ` Jiayuan Chen
2026-10-23 9:13 ` [PATCH net 3/5] ipv6: restrict mld_qrv to 255 Jiayuan Chen
2026-10-23 14:13 ` Fernando Fernandez Mancera
2026-10-23 9:13 ` [PATCH net 4/5] ipv4: restrict igmp_qrv " Jiayuan Chen
2026-10-23 14:14 ` Fernando Fernandez Mancera [this message]
2026-10-23 9:13 ` [PATCH net 5/5] net: restrict message_cost and message_burst to non-negative values Jiayuan Chen
2026-10-23 12:19 ` Joel Granados
2026-10-23 12:55 ` Fernando Fernandez Mancera
2026-10-23 14:30 ` Jiayuan Chen
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