From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) (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 93A864DAFB2; Fri, 9 Oct 2026 13:21:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791552068; cv=none; b=Sw1jcoW3vVaB2kjFxsQ6fYPjIKZoh3KJD40Nz1+sRnbCdGwMIbaJILMy7Oa+hTtUFsWeWmOSeSX22Yp2DOTBGvgsrmGSpUWFJVYbJ7rByUtQXNkK27mHQsVvWSBxmdIrihQAWyXAdcTLTMOx0gw5wdmH6sVp65X2h58fK6pvelk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791552068; c=relaxed/simple; bh=AUj7OySEVuzLrRKTI2/u/OTDShpb6BsJbutuegVE7Yo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=PMqm2uQof/uHisLbo9RjYoOZdlBtymNvyPPvWYDbmYZmg858+d2e8FC3D7X6qiYDuXFbMO/GjqGmfaN0eKT95K0xYabEw3DI+7U9/cBjI4fJHu6McHGd3d/tA4qR9KXjevaNc82Nn79pV9r4eLY+myjVKKan7fMFOBXvqUI8K/M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=QRE7GzXF; arc=none smtp.client-ip=220.197.31.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="QRE7GzXF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=UJ R/c+njOjwBClCYT0vYB+8OCVlBHF2A3nn7qINygic=; b=QRE7GzXFD+fn0WZci7 wH594ex4QlL7GMMwU0Gc/nPjtUQYPtMby8rrAZ8Nm4RlYWdtuWg7yphhioTUtFe5 AUWiyXBkFd34gxDGe7W79ETj1WCivx5ey7yNQi9B3blQsqt7ixQgE8UOgO+AJNy9 SdcdBZBVCs6qhsT6c1omMhQ68= Received: from colol4bi5.localdomain (unknown []) by gzga-smtp-mtada-g1-2 (Coremail) with SMTP id _____wD3P_wX6shqSb62DQ--.56277S2; Fri, 09 Oct 2026 21:20:24 +0800 (CST) From: Binbin Deng <18983559317@163.com> To: sam@mendozajonas.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Binbin Deng <18983559317@163.com> Subject: [PATCH net v1] ncsi: Fix use-after-free in the device unregister path Date: Fri, 9 Oct 2026 21:20:21 +0800 Message-ID: <20261009132021.39611-1-18983559317@163.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3P_wX6shqSb62DQ--.56277S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxCFy8ArW3Cr48tr1fKw15Jwb_yoWrGw1fpF W3GryrKw48JF1FgFZ5WrWrWF15Xr4kW3Wjg39rKw4Sya9xGryUZryrAay09Fy5GFZ7Ca1a vr4YgF4a9rW8ZrJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07Uc0eXUUUUU= X-CM-SenderInfo: jprymmytvvmjmrxbiqqrwthudrp/xtbC3xiNcWrI6hh-CgAA3e ncsi_unregister_dev() tears the NCSI device down in this order: dev_remove_pack(&ndp->ptype); list_for_each_entry_safe(np, tmp, &ndp->packages, node) ncsi_remove_package(np); ... disable_work_sync(&ndp->work); kfree(ndp); ncsi_remove_package() and ncsi_remove_channel() remove the objects with list_del_rcu() and free them with an immediate kfree(). Two concurrent users are not covered by this sequence: 1. The NCSI state machine work (ndp->work) iterates the package and channel lists (NCSI_FOR_EACH_PACKAGE/NCSI_FOR_EACH_CHANNEL, which are list_for_each_entry_rcu) while configuring channels, holding neither ndp->lock nor np->lock across the iteration. disable_work_sync() runs only after all packages have been freed, so it does not prevent the work from walking the lists over freed objects. 2. RCU readers of the published lists. list_del_rcu() removes the entry for subsequent readers, but the following bare kfree() is not covered by any grace period, so a reader that has already obtained the node pointer (e.g. a list_for_each_entry_rcu iteration in flight) dereferences freed memory when it resumes. The ordering is reachable on BMC systems: ftgmac100_remove() calls ncsi_unregister_dev() before unregister_netdev(), i.e. before ncsi_stop_dev() has stopped the state machine, so the work is still active while the packages are freed. Device removal concurrent with the NCSI configuration cycle or a netlink query triggers the race. Fix this in two parts: - stop the state machine work before freeing the packages and channels instead of after; - free the package and channel objects with kfree_rcu() so that readers covered by an RCU read-side critical section do not access freed memory. Fixes: e6f44ed6d04d ("net/ncsi: Package and channel management") Signed-off-by: Binbin Deng <18983559317@163.com> --- net/ncsi/internal.h | 2 ++ net/ncsi/ncsi-manage.c | 8 ++++---- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/net/ncsi/internal.h b/net/ncsi/internal.h index 2c9d1f22c16a..461469cc2600 100644 --- a/net/ncsi/internal.h +++ b/net/ncsi/internal.h @@ -239,6 +239,7 @@ struct ncsi_channel { } monitor; struct list_head node; struct list_head link; + struct rcu_head rcu_head; }; struct ncsi_package { @@ -253,6 +254,7 @@ struct ncsi_package { bool multi_channel; /* Enable multiple channels */ u32 channel_whitelist; /* Channels to configure */ struct ncsi_channel *preferred_channel; /* Primary channel */ + struct rcu_head rcu_head; }; struct ncsi_request { diff --git a/net/ncsi/ncsi-manage.c b/net/ncsi/ncsi-manage.c index 1d63958c4429..39ac7075cd1b 100644 --- a/net/ncsi/ncsi-manage.c +++ b/net/ncsi/ncsi-manage.c @@ -263,7 +263,7 @@ static void ncsi_remove_channel(struct ncsi_channel *nc) np->channel_num--; spin_unlock_irqrestore(&np->lock, flags); - kfree(nc); + kfree_rcu(nc, rcu_head); } struct ncsi_package *ncsi_find_package(struct ncsi_dev_priv *ndp, @@ -326,7 +326,7 @@ void ncsi_remove_package(struct ncsi_package *np) ndp->package_num--; spin_unlock_irqrestore(&ndp->lock, flags); - kfree(np); + kfree_rcu(np, rcu_head); } void ncsi_find_package_and_channel(struct ncsi_dev_priv *ndp, @@ -1958,6 +1958,8 @@ void ncsi_unregister_dev(struct ncsi_dev *nd) struct ncsi_package *np, *tmp; unsigned long flags; + disable_work_sync(&ndp->work); + dev_remove_pack(&ndp->ptype); list_for_each_entry_safe(np, tmp, &ndp->packages, node) @@ -1967,8 +1969,6 @@ void ncsi_unregister_dev(struct ncsi_dev *nd) list_del_rcu(&ndp->node); spin_unlock_irqrestore(&ncsi_dev_lock, flags); - disable_work_sync(&ndp->work); - kfree(ndp); } EXPORT_SYMBOL_GPL(ncsi_unregister_dev); -- 2.43.0