From: Ido Schimmel <idosch@nvidia.com>
To: Jiayuan Chen <jiayuan.chen@linux.dev>
Cc: netdev@vger.kernel.org, David Ahern <dsahern@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
Omid Ehtemam-Haghighi <omid.ehtemamhaghighi@menlosecurity.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net 1/2] ipv6: fix possible infinite loop in rt6_fill_node()
Date: Thu, 28 May 2026 11:45:02 +0300 [thread overview]
Message-ID: <20260528084502.GA592092@shredder> (raw)
In-Reply-To: <20260527053133.180695-1-jiayuan.chen@linux.dev>
On Wed, May 27, 2026 at 01:31:30PM +0800, Jiayuan Chen wrote:
> Sashiko reported this issue [1]. Apply the same fix as
> commit f8d8ce1b515a ("ipv6: fix possible infinite loop in fib6_info_uses_dev()").
>
> Writers holding tb6_lock can list_del_rcu(&rt->fib6_siblings)
> without waiting for RCU readers; rt->fib6_siblings.next then still
> points into the old ring and this softirq-side walker never reaches
> &rt->fib6_siblings, causing a CPU stall. fib6_purge_rt() always
s/fib6_purge_rt/fib6_del_route/ ?
> WRITE_ONCE()s rt->fib6_nsiblings to 0 before list_del_rcu(), so an
> inside-loop check is a reliable detach signal.
>
> [1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev
>
> Fixes: d9ccb18f83ea ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn")
> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Sashiko points out two pre-existing issues:
1. Same issue in nft_fib6_info_nh_uses_dev(). Fixed by:
https://lore.kernel.org/all/20260526020227.4857-1-jiayuan.chen@linux.dev/
2. Missing nlmsg_{end, cancel}() following ip6mr_get_route(). Seems
valid, but completely unrelated.
next prev parent reply other threads:[~2026-05-28 8:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-27 5:31 [PATCH net 1/2] ipv6: fix possible infinite loop in rt6_fill_node() Jiayuan Chen
2026-05-27 5:31 ` [PATCH net 2/2] ipv6: fix possible infinite loop in fib6_select_path() Jiayuan Chen
2026-05-28 8:45 ` Ido Schimmel
2026-05-28 8:45 ` Ido Schimmel [this message]
2026-05-28 8:56 ` [PATCH net 1/2] ipv6: fix possible infinite loop in rt6_fill_node() Jiayuan Chen
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