From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FD271A6803; Tue, 16 Jun 2026 16:45:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781628355; cv=none; b=jnkTisdDsPSr1R4HuItmFX+AalO6cq89BYgi6CE2v5ex3NVFKQdDtgbKMEV9yDAnyTiADWClBPfjuVQBfs2/cXm5H7GGTmo0Qo1AQM7at3EkMZHrj1YJrfExr/JzSv3e3vZvOeS3xl//JgB/iva7u4a8n+YBrXfA7mdKmnSOVok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781628355; c=relaxed/simple; bh=xP65VsI00YADUrgQDhy3X3Jm+YgPBt+ri5T5sjNqCCs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=abpFIJI3SqS7pAj2hfrITYjM3Ae/dyjBJC0xYrtmJpKqRul9I4xysizr7U8bx7Jvi856VU8pEZPkSqE1atl54wcnjo6toQDJ4Ttzr8sKSuxF+opiOPFgFDPm3guIQOLhhEEjIJ1Jkr28RHpXyaTQFAl/+gnHhU7NDT7GWP9exXc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CsbgBwwc; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CsbgBwwc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E5641F000E9; Tue, 16 Jun 2026 16:45:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781628354; bh=bH7C9KqTeLiUhoDVxk8n06zsxsQi+eMJWDsepaoJigc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CsbgBwwc6I+MNB01kF83O/aNKhyVO2TjKpod+fS3uTJiO0hh3duVxIouMBR0dU7cY hZq/AYID0Eko0nJQ8kKMHp4BaI7aYi+jQeohIVvKS/1WEtoSDOvkcoGIXmqCzJhnIt fl31E+LxsyHabIqA5PeERygqcpGNL7BwhwiOGyQY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiayuan Chen , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 046/452] ipv6: fix possible infinite loop in rt6_fill_node() Date: Tue, 16 Jun 2026 20:24:33 +0530 Message-ID: <20260616145120.354944538@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145117.796205997@linuxfoundation.org> References: <20260616145117.796205997@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiayuan Chen [ Upstream commit 9f72412bcf60144f252b0d6205106abf14344abc ] 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_del_route() always 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 Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260527053133.180695-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv6/route.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index c5b71baf95e7b3..69659f2a6aea96 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -5797,6 +5797,8 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb, goto nla_put_failure; } + if (!READ_ONCE(rt->fib6_nsiblings)) + break; } rcu_read_unlock(); -- 2.53.0