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 03BF01F4735; Tue, 17 Dec 2024 17:09:44 +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=1734455385; cv=none; b=pNmTE6eaPMcIGDeYBCzOe658VCm6iOlqFRZE90jctOqPYwq4JuJTNPtwQdRavLiJvC5v9T98h/e91Ke5/ysWZE+dU1vZiLXvAsYWwvIxjcKfDCl7P3TlwM84HQLh4+68evqdD0682RR0Hb8fMt8fgXrjgMlzurxm7T2+7BrfEns= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734455385; c=relaxed/simple; bh=zMq/2gc9i7ZBTQFF1TEOMX4avfK9xSOgBQCbpvUcZZQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JTUbwXhvTvxa4MCV+F0qW0aWLDcUDXcjHYxsH1tDdvyVju0b3mvY6y05TC7B5VlVlKdRQCGwGLGhK63whwHfWi2YcR7nrekut9f7HawUheQ3+tgCCRKZ0YiRcZPp0AvnaHFYHzfzkQw2e+uUiPkNppP892qA7NvN5tFyKnjQy1M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=H7notOE6; 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="H7notOE6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29B3DC4CED3; Tue, 17 Dec 2024 17:09:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734455384; bh=zMq/2gc9i7ZBTQFF1TEOMX4avfK9xSOgBQCbpvUcZZQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H7notOE6OyGZtW0g/hp4U/WW7lYWHBTGCfNFFZnKt5kvjLSUWj4qLJrHv0/HLt37u JJ7B8f5H3HFyXm7WJJD/8eDppxz8l8WpqDePNUyPNaWFpa7UEw5H7rGCzkVFl4jP3N 1PJnAvPaVM8D2Fbe6VmPPByuhyIO5cRg9dTolefQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Prashanth K , Lianqin Hu Subject: [PATCH 5.4 05/24] usb: gadget: u_serial: Fix the issue that gs_start_io crashed due to accessing null pointer Date: Tue, 17 Dec 2024 18:07:03 +0100 Message-ID: <20241217170519.227130081@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241217170519.006786596@linuxfoundation.org> References: <20241217170519.006786596@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 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lianqin Hu commit 4cfbca86f6a8b801f3254e0e3c8f2b1d2d64be2b upstream. Considering that in some extreme cases, when u_serial driver is accessed by multiple threads, Thread A is executing the open operation and calling the gs_open, Thread B is executing the disconnect operation and calling the gserial_disconnect function,The port->port_usb pointer will be set to NULL. E.g. Thread A Thread B gs_open() gadget_unbind_driver() gs_start_io() composite_disconnect() gs_start_rx() gserial_disconnect() ... ... spin_unlock(&port->port_lock) status = usb_ep_queue() spin_lock(&port->port_lock) spin_lock(&port->port_lock) port->port_usb = NULL gs_free_requests(port->port_usb->in) spin_unlock(&port->port_lock) Crash This causes thread A to access a null pointer (port->port_usb is null) when calling the gs_free_requests function, causing a crash. If port_usb is NULL, the release request will be skipped as it will be done by gserial_disconnect. So add a null pointer check to gs_start_io before attempting to access the value of the pointer port->port_usb. Call trace: gs_start_io+0x164/0x25c gs_open+0x108/0x13c tty_open+0x314/0x638 chrdev_open+0x1b8/0x258 do_dentry_open+0x2c4/0x700 vfs_open+0x2c/0x3c path_openat+0xa64/0xc60 do_filp_open+0xb8/0x164 do_sys_openat2+0x84/0xf0 __arm64_sys_openat+0x70/0x9c invoke_syscall+0x58/0x114 el0_svc_common+0x80/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x38/0x68 Fixes: c1dca562be8a ("usb gadget: split out serial core") Cc: stable@vger.kernel.org Suggested-by: Prashanth K Signed-off-by: Lianqin Hu Acked-by: Prashanth K Link: https://lore.kernel.org/r/TYUPR06MB62178DC3473F9E1A537DCD02D2362@TYUPR06MB6217.apcprd06.prod.outlook.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_serial.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -566,9 +566,12 @@ static int gs_start_io(struct gs_port *p * we didn't in gs_start_tx() */ tty_wakeup(port->port.tty); } else { - gs_free_requests(ep, head, &port->read_allocated); - gs_free_requests(port->port_usb->in, &port->write_pool, - &port->write_allocated); + /* Free reqs only if we are still connected */ + if (port->port_usb) { + gs_free_requests(ep, head, &port->read_allocated); + gs_free_requests(port->port_usb->in, &port->write_pool, + &port->write_allocated); + } status = -EIO; }