From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 001793E959D; Tue, 14 Apr 2026 15:40:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776181202; cv=none; b=IT4AVnco9XvSVRRWUUp4Tt8erMIssOfdSqcRKnORSR63oTR8jo7VxtOjFrWamMej3zmPbB9aFEEfcHX3GZ4g9k+HCYWfMKcf+/RXdm+vRGeipZQCRF8/AjEy4Aplr0e/cco6xR6R9uxJbUnY1ejQOoxwhwdmKugHnO7xeDgTJ38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776181202; c=relaxed/simple; bh=g9XpWWz1SxVgb0pf9yHfFzddWuvrZobpuA6QIzfLLWg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rKZhLCNZLbmslHsu2MP1RQFzVXdlGuYuz7umvW/aXlvv8CVIqGAF6MJe5yJ22NHbYhiZscTpX4+5SU1gM406+8eE1AFMljztM+Q3BekEVHXxrf2IxqKq+1juT5BY8zO0dV91oprdkeuQ/RJ8QKwSTG//eF+3+WjaLt/2Qzngxns= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b=dPXEwOuX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="dPXEwOuX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA9EDC19425; Tue, 14 Apr 2026 15:40:00 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="dPXEwOuX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1776181199; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1OD9H9fIMPiOoqvYQ6ai2yEsDn71I8Os81Ip4a3JthM=; b=dPXEwOuXVjKNIr+HKgbWP1iCVk1plqJU7/aK+doi02LwHMdWaXPFrmfm//88fGiRYuaMNM dtu90IMV95YIYE9w8DyDCqPMUNWvWf+7cNR748odHshi8sVRCKgl3snq8k16jVJPFuKIbh FHCF5eikD9JcmkVYYxEryfoN6w4xT+8= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id c3676861 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 14 Apr 2026 15:39:59 +0000 (UTC) From: "Jason A. Donenfeld" To: netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com Cc: Shardul Bankar , syzbot+f2fbf7478a35a94c8b7c@syzkaller.appspotmail.com, stable@vger.kernel.org, "Jason A. Donenfeld" Subject: [PATCH net-next 4/4] wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit Date: Tue, 14 Apr 2026 17:39:44 +0200 Message-ID: <20260414153944.2742252-5-Jason@zx2c4.com> In-Reply-To: <20260414153944.2742252-1-Jason@zx2c4.com> References: <20260414153944.2742252-1-Jason@zx2c4.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Shardul Bankar wg_netns_pre_exit() manually acquires rtnl_lock() inside the pernet .pre_exit callback. This causes a hung task when another thread holds rtnl_mutex - the cleanup_net workqueue (or the setup_net failure rollback path) blocks indefinitely in wg_netns_pre_exit() waiting to acquire the lock. Convert to .exit_rtnl, introduced in commit 7a60d91c690b ("net: Add ->exit_rtnl() hook to struct pernet_operations."), where the framework already holds RTNL and batches all callbacks under a single rtnl_lock()/rtnl_unlock() pair, eliminating the contention window. The rcu_assign_pointer(wg->creating_net, NULL) is safe to move from .pre_exit to .exit_rtnl (which runs after synchronize_rcu()) because all RCU readers of creating_net either use maybe_get_net() - which returns NULL for a dying namespace with zero refcount - or access net->user_ns which remains valid throughout the entire ops_undo_list sequence. Reported-by: syzbot+f2fbf7478a35a94c8b7c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?id=cb64c22a492202ca929e18262fdb8cb89e635c70 Signed-off-by: Shardul Bankar [ Jason: added __net_exit and __read_mostly annotations that were missing. ] Fixes: 900575aa33a3 ("wireguard: device: avoid circular netns references") Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld --- drivers/net/wireguard/device.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c index 46a71ec36af87..67b07ee2d6600 100644 --- a/drivers/net/wireguard/device.c +++ b/drivers/net/wireguard/device.c @@ -411,12 +411,11 @@ static struct rtnl_link_ops link_ops __read_mostly = { .newlink = wg_newlink, }; -static void wg_netns_pre_exit(struct net *net) +static void __net_exit wg_netns_exit_rtnl(struct net *net, struct list_head *dev_kill_list) { struct wg_device *wg; struct wg_peer *peer; - rtnl_lock(); list_for_each_entry(wg, &device_list, device_list) { if (rcu_access_pointer(wg->creating_net) == net) { pr_debug("%s: Creating namespace exiting\n", wg->dev->name); @@ -429,11 +428,10 @@ static void wg_netns_pre_exit(struct net *net) mutex_unlock(&wg->device_update_lock); } } - rtnl_unlock(); } -static struct pernet_operations pernet_ops = { - .pre_exit = wg_netns_pre_exit +static struct pernet_operations pernet_ops __read_mostly = { + .exit_rtnl = wg_netns_exit_rtnl }; int __init wg_device_init(void) -- 2.53.0