From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
To: Yuyang Huang <yuyanghuang@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
David Ahern <dsahern@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Ido Schimmel <idosch@nvidia.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH net-next] ipv4: igmp: remove multicast group from hash table on device destruction
Date: Wed, 10 Jun 2026 09:50:10 +0200 [thread overview]
Message-ID: <fdcc6f4b-6f81-4422-bfbc-7376dd5cd19f@6wind.com> (raw)
In-Reply-To: <20260609122646.2297540-1-yuyanghuang@google.com>
Le 09/06/2026 à 14:26, Yuyang Huang a écrit :
> When a device is destroyed under RTNL, ip_mc_destroy_dev() iterates through
> the multicast list and calls ip_ma_put() on each membership, scheduling
> them for RCU reclamation. However, they are not unlinked from the device's
> multicast hash table (mc_hash).
>
> Since the device remains published in dev->ip_ptr until after
> ip_mc_destroy_dev() completes, concurrent RCU readers traversing mc_hash
> can still locate and access the multicast group after its refcount is
> decremented. If the RCU callback runs and frees the group while a reader is
> accessing it, a use-after-free occurs.
>
> Fix this by unlinking the multicast group from mc_hash using
> ip_mc_hash_remove() before scheduling it for reclamation.
>
> Signed-off-by: Yuyang Huang <yuyanghuang@google.com>
A 'Fixes' tag may be useful for backports.
Regards,
Nicolas
next prev parent reply other threads:[~2026-06-10 7:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-09 12:26 Yuyang Huang
2026-06-10 7:50 ` Nicolas Dichtel [this message]
2026-06-10 8:37 ` Yuyang Huang
2026-06-10 8:52 ` Nicolas Dichtel
2026-06-10 10:56 ` Yuyang Huang
2026-06-14 0:29 ` Yuyang Huang
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