From: "Linus Lüssing" <linus.luessing@c0d3.blue>
To: Sven Eckelmann <sven@narfation.org>
Cc: b.a.t.m.a.n@lists.open-mesh.org
Subject: Re: [PATCH RFC batadv] batman-adv: mcast: fix use-after-free in orig_node RCU release
Date: Sun, 17 May 2026 23:08:30 +0200 [thread overview]
Message-ID: <agouTnSEU6CuTF5i@sellars> (raw)
In-Reply-To: <20260514-mcast-rcu-list-free-v1-1-0e20f24faa61@narfation.org>
On Thu, May 14, 2026 at 07:41:38PM +0200, Sven Eckelmann wrote:
> batadv_mcast_purge_orig() removes entries from RCU-protected hlists but
> does not wait for an RCU grace period before returning. Concurrent RCU
> readers may still accesses references to those entries at the point of
> removal. RCU-protected readers trying to operate on entries like
> orig->mcast_want_all_ipv6_node will then access already freed memory.
>
> Fix this by moving batadv_mcast_purge_orig() to batadv_orig_node_release(),
> just before the call_rcu() invocation. This ensures RCU readers that were
> active at purge time have drained before the orig_node memory is reclaimed.
>
> Fixes: 1c090349e2f6 ("batman-adv: Add IPv4 link-local/IPv6-ll-all-nodes multicast support")
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
Makes sense to me now and does not seem to crash on my laptop with
Debian Sid in a simple batadv/veth setup.
Acked-by: Linus Lüssing <linus.luessing@c0d3.blue>
prev parent reply other threads:[~2026-05-17 21:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-14 17:41 [PATCH RFC batadv] batman-adv: mcast: fix use-after-free in orig_node RCU release Sven Eckelmann
2026-05-17 16:38 ` Linus Lüssing
2026-05-17 16:54 ` Sven Eckelmann
2026-05-17 17:55 ` Linus Lüssing
2026-05-17 18:08 ` Sven Eckelmann
2026-05-17 21:08 ` Linus Lüssing [this message]
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