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 2AAEF3E92A5; Tue, 31 Mar 2026 16:26:58 +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=1774974418; cv=none; b=BzSnhjD4LOfshqbB1SgJtFOhr5lO+ykoP63cVUNtjRPYiITGgVLQdiFyS/CKLPJLH7OJTrLMlLupNzvuhO8A2/jiQKPw8Y4bG0tMTHTbgsJ6YK8288URXfINkR7B505HffJZycX3k5VnJFwAMa64BYfICcZrHUNNZliclou4cnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774974418; c=relaxed/simple; bh=ff/J5qTE2wHjkj+cgxCqZJmGlozOVC8IudAxnw20mVs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GPq0uZl/w7wHCBwtu3Poj035efD6wO1okJY6kW0JE6lnDTQjyZjZVXQoicRwao1YDu50+t3SyV0Y0RwvRF+N1XH1rvDjg7PtL9lQgkBL9X7z19/LZ+MMlXljCzpJyDmabrFpoc0SXA142yqj5DI4roi1w4Rd1efyA/RQfJVUEXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=q9O/lVd9; 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="q9O/lVd9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B57A1C19423; Tue, 31 Mar 2026 16:26:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774974418; bh=ff/J5qTE2wHjkj+cgxCqZJmGlozOVC8IudAxnw20mVs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q9O/lVd99nNhKaq+WOGxIYODxoH5Z1qkyf4ShzlDY4Ztc5wtDOZBBWitCROzwZLyL 1OhUKCgPhQgERcQ6fr5VTjO4tLYL2V8MsJyV82GYFxFBLw6acRErDnHjOo7UqcZdrY 41tmokIAukbxRUtYq83s5Usp7hEvOf7djTLHD+zo= 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 6.6 045/175] nfc: nci: fix circular locking dependency in nci_close_device Date: Tue, 31 Mar 2026 18:20:29 +0200 Message-ID: <20260331161731.441220906@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161729.779738837@linuxfoundation.org> References: <20260331161729.779738837@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 6.6-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 1f33da345bea6..e2ffdb06bf9aa 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -575,8 +575,7 @@ 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 */ @@ -588,13 +587,13 @@ 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); del_timer_sync(&ndev->cmd_timer); @@ -604,6 +603,9 @@ 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