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 AA03D2D5C68; Tue, 31 Mar 2026 17:00:35 +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=1774976435; cv=none; b=GhhrhSVtSdTUbPY9hrk+lJonM//oeLb8LkEm9B9i7GM0KAxaR1efnS4AoKnYZpFBREWonvLzaTtc8VNyJ3kZdIPlmWZEfpC47fSFEYm3CSyb4gQiTRzVMAtnbLXeadvLytDWjZZaByrWjMrZQ6jhw+hA/FaQHgWeFZGQzekiV3A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976435; c=relaxed/simple; bh=NpdDV44e8Uzu+lY2RVNngfpErlueErbP5Hk2ppdruDY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OnUzoszi1Ds63YBRtmxJFbFjR67cTrJ1N1ojQA4M6/rr9QZn1WbVqYlr0Wu9sVYNE5H+bgc6j72Pgqgq3+yflJO2tDYXQkIW+QiHQuhIsWWt9NLFbpI8k8Hk3c3Fb3vL4JzdGCWjaPvkFafzIuMqXYh5EaZPYhzi7GEGkP9/zGY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TO54BdJ6; 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="TO54BdJ6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BA65C2BCB4; Tue, 31 Mar 2026 17:00:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774976435; bh=NpdDV44e8Uzu+lY2RVNngfpErlueErbP5Hk2ppdruDY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TO54BdJ6HbBmmd+KhKTd1ptNPR0BgklbaYB8HULjrOoYqRr8qJR17YDT7OJX57nfd re4cNJDyYSkcnKzCDVgjzoiphnunlG5CvlDCfLdiEUppKnLbtrLNb9RT7ehU8QuWBD Nfw0NGBflfs0zchfZsBhKxXhmdQE//o90WCkGdq0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ian Ray , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 090/309] nfc: nci: fix circular locking dependency in nci_close_device Date: Tue, 31 Mar 2026 18:19:53 +0200 Message-ID: <20260331161756.804683378@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Kicinski [ Upstream commit 4527025d440ce84bf56e75ce1df2e84cb8178616 ] nci_close_device() flushes rx_wq and tx_wq while holding req_lock. This causes a circular locking dependency because nci_rx_work() running on rx_wq can end up taking req_lock too: nci_rx_work -> nci_rx_data_packet -> nci_data_exchange_complete -> __sk_destruct -> rawsock_destruct -> nfc_deactivate_target -> nci_deactivate_target -> nci_request -> mutex_lock(&ndev->req_lock) Move the flush of rx_wq after req_lock has been released. This should safe (I think) because NCI_UP has already been cleared and the transport is closed, so the work will see it and return -ENETDOWN. NIPA has been hitting this running the nci selftest with a debug kernel on roughly 4% of the runs. Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation") Reviewed-by: Ian Ray Link: https://patch.msgid.link/20260317193334.988609-1-kuba@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/nfc/nci/core.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index d334b7aa8c172..25ba4cbb00e1e 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -579,8 +579,7 @@ static int nci_close_device(struct nci_dev *ndev) skb_queue_purge(&ndev->rx_q); skb_queue_purge(&ndev->tx_q); - /* Flush RX and TX wq */ - flush_workqueue(ndev->rx_wq); + /* Flush TX wq, RX wq flush can't be under the lock */ flush_workqueue(ndev->tx_wq); /* Reset device */ @@ -592,13 +591,13 @@ static int nci_close_device(struct nci_dev *ndev) msecs_to_jiffies(NCI_RESET_TIMEOUT)); /* After this point our queues are empty - * and no works are scheduled. + * rx work may be running but will see that NCI_UP was cleared */ ndev->ops->close(ndev); clear_bit(NCI_INIT, &ndev->flags); - /* Flush cmd wq */ + /* Flush cmd and tx wq */ flush_workqueue(ndev->cmd_wq); timer_delete_sync(&ndev->cmd_timer); @@ -613,6 +612,9 @@ static int nci_close_device(struct nci_dev *ndev) mutex_unlock(&ndev->req_lock); + /* rx_work may take req_lock via nci_deactivate_target */ + flush_workqueue(ndev->rx_wq); + return 0; } -- 2.51.0