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 9D94534A3D6; Fri, 21 Nov 2025 13:34:42 +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=1763732082; cv=none; b=ITIcc8mDO9uociWd9aTVQVEjjbmNR06BemjYmOsGRZvjgilhdld5/gYfvM2Mu34IyT9D2AdWlfMiO8GqmtELBHxUxAIh8jNWcrLKOyhKYCMqLGtpXIOTiPcwJRpp+xbHj5vX3to8uIpUrYRfDOsqefdZ6mkfRQaRdo4N5LfxfTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763732082; c=relaxed/simple; bh=SUjsGuwl9b7Mb/aom4LM8nG8B/F9WMLZm1mE6NbYFAQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C42DILqZNpj3eelN9Ljpo950c23nJ83YLm6maUZiXO+BYHKKeSHIs/UaRS/Pffr4tWx2wR8NLAfFEy6kveyoRB/ZyECA21vT+U8v2ByaZmABYlM50HG/Cdc7zlE3K8NzljMC63jCPXdD9G0nccqmkr5KaIViK6FjhPPpDTKcyFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YhEZ0NXB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YhEZ0NXB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29A20C4CEF1; Fri, 21 Nov 2025 13:34:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1763732082; bh=SUjsGuwl9b7Mb/aom4LM8nG8B/F9WMLZm1mE6NbYFAQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YhEZ0NXBDjZprdJLSW3cxwOZh/Eo6j/YoR7LgSoRJGIywV8rJIM4swEt7FzjjLAYF ttcR5+Tm4HKID9lM4wdY3gq5Jw9jvZyEB/eMdWyWAGAdmWtGJ8ELX1GJLflLtJ4wjR gsnidOvZy5XJIVdQHjQbfj4fDoaIC4cbZqyRMtJM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, John Sperbeck , Breno Leitao , Jakub Kicinski Subject: [PATCH 6.12 183/185] net: netpoll: ensure skb_pool list is always initialized Date: Fri, 21 Nov 2025 14:13:30 +0100 Message-ID: <20251121130150.496089741@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251121130143.857798067@linuxfoundation.org> References: <20251121130143.857798067@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: John Sperbeck commit f0d0277796db613c124206544b6dbe95b520ab6c upstream. When __netpoll_setup() is called directly, instead of through netpoll_setup(), the np->skb_pool list head isn't initialized. If skb_pool_flush() is later called, then we hit a NULL pointer in skb_queue_purge_reason(). This can be seen with this repro, when CONFIG_NETCONSOLE is enabled as a module: ip tuntap add mode tap tap0 ip link add name br0 type bridge ip link set dev tap0 master br0 modprobe netconsole netconsole=4444@10.0.0.1/br0,9353@10.0.0.2/ rmmod netconsole The backtrace is: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page ... ... ... Call Trace: __netpoll_free+0xa5/0xf0 br_netpoll_cleanup+0x43/0x50 [bridge] do_netpoll_cleanup+0x43/0xc0 netconsole_netdev_event+0x1e3/0x300 [netconsole] unregister_netdevice_notifier+0xd9/0x150 cleanup_module+0x45/0x920 [netconsole] __se_sys_delete_module+0x205/0x290 do_syscall_64+0x70/0x150 entry_SYSCALL_64_after_hwframe+0x76/0x7e Move the skb_pool list setup and initial skb fill into __netpoll_setup(). Fixes: 221a9c1df790 ("net: netpoll: Individualize the skb pool") Signed-off-by: John Sperbeck Reviewed-by: Breno Leitao Link: https://patch.msgid.link/20250114011354.2096812-1-jsperbeck@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/netpoll.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -632,6 +632,8 @@ int __netpoll_setup(struct netpoll *np, const struct net_device_ops *ops; int err; + skb_queue_head_init(&np->skb_pool); + if (ndev->priv_flags & IFF_DISABLE_NETPOLL) { np_err(np, "%s doesn't support polling, aborting\n", ndev->name); @@ -667,6 +669,9 @@ int __netpoll_setup(struct netpoll *np, strscpy(np->dev_name, ndev->name, IFNAMSIZ); npinfo->netpoll = np; + /* fill up the skb queue */ + refill_skbs(np); + /* last thing to do is link it to the net device structure */ rcu_assign_pointer(ndev->npinfo, npinfo); @@ -686,8 +691,6 @@ int netpoll_setup(struct netpoll *np) struct in_device *in_dev; int err; - skb_queue_head_init(&np->skb_pool); - rtnl_lock(); if (np->dev_name[0]) { struct net *net = current->nsproxy->net_ns; @@ -787,9 +790,6 @@ put_noaddr: } } - /* fill up the skb queue */ - refill_skbs(np); - err = __netpoll_setup(np, ndev); if (err) goto flush;