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 CA5B91C07FF; Tue, 15 Oct 2024 13:06:26 +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=1728997586; cv=none; b=rY+tbJDH5HyMK2/zuC2QGt/uFzaXoZB8jVT7toPxsOkLp9Bb/6uUv1IQdb4h41eNjZ4lpUjz2Cb5bj0k3Cbd5Mhg7jbtiCv0GKTd7nvBSTp1/nuTPvicko6xM1kv/FJuUXqNNADDy53a8bj+Yw9IbOkyU0UAFEjF8cxP2bp4e5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728997586; c=relaxed/simple; bh=R43xR5LiByC471C2ZifXsJbgTOucQCPr5DRRE5VGxYQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pU2bE+1AQQV7+5UG1mZP2XNWMovx9wZC1cdCPKb5KhTbtE+d9T9MFvpdm/DND4sSucKPAvMF83O7ex+/cAwEBVXJow+k0X/730a29bzPtbsJuj1W2iA9cvOm7ZiMmOYNi044c/uS/lBQTRw/Z3m5m+fRM2HUZck2V2BDKHyPd7U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hUlNLn4Y; 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="hUlNLn4Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B25FC4CEC6; Tue, 15 Oct 2024 13:06:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728997586; bh=R43xR5LiByC471C2ZifXsJbgTOucQCPr5DRRE5VGxYQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hUlNLn4YPDmuTX9SPK6UWN0JW4h2w1Qz5rpVlWe/LvWej9NL3N3SW6YbCZVtWZXux Tb2FRPfrELHB4lgrVZ3DQYLHaIO0MMDsTBP6mvzRxsycERHCOpdf2Akw2RelciGdtX 5v+CUWc/0/KpYvznMYQDBSY802EieRNlU05bofmk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oliver Neukum , stable Subject: [PATCH 5.10 226/518] USB: class: CDC-ACM: fix race between get_serial and set_serial Date: Tue, 15 Oct 2024 14:42:10 +0200 Message-ID: <20241015123925.719933128@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015123916.821186887@linuxfoundation.org> References: <20241015123916.821186887@linuxfoundation.org> User-Agent: quilt/0.67 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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oliver Neukum commit b41c1fa155ba56d125885b0191aabaf3c508d0a3 upstream. TIOCGSERIAL is an ioctl. Thus it must be atomic. It returns two values. Racing with set_serial it can return an inconsistent result. The mutex must be taken. In terms of logic the bug is as old as the driver. In terms of code it goes back to the conversion to the get_serial and set_serial methods. Signed-off-by: Oliver Neukum Cc: stable Fixes: 99f75a1fcd865 ("cdc-acm: switch to ->[sg]et_serial()") Link: https://lore.kernel.org/r/20240912141916.1044393-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -942,10 +942,12 @@ static int get_serial_info(struct tty_st struct acm *acm = tty->driver_data; ss->line = acm->minor; + mutex_lock(&acm->port.mutex); ss->close_delay = jiffies_to_msecs(acm->port.close_delay) / 10; ss->closing_wait = acm->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? ASYNC_CLOSING_WAIT_NONE : jiffies_to_msecs(acm->port.closing_wait) / 10; + mutex_unlock(&acm->port.mutex); return 0; }