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 3843222259F; Mon, 20 Apr 2026 15:56:06 +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=1776700566; cv=none; b=FHcaeVKZ3mAzV4BYS0wQn5Uqsq4FbcJo+GradKEDIj9M2lwK6SQ4YbnyP6WCcDA8A3N+C+QU54X13XpvcQ8ZeQPeAeOciXiXHm5TiN/OEk/aR/H8iAH0h5cFTWLU8GQLvIJlqJuI3Tm1SHlewUn4DxyNTcAjCGh3WM6h4+c/lqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776700566; c=relaxed/simple; bh=jWeBgu6Il0RwgxJt3SnjG5DkiWdpc6D5fXK398/u1KY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AZNFsdCgh8g9hQa4n5RpB/YR0zUw3pRHz246DYTNpQZZlzc8LGOD5MMXF5dS3K3dgRVdKcko5LbjgHSxJHikNFOmYKIpmXBnFm4Z4IjDqHvqeA19yY5Y/kmvp1z6N6XOKJ7Wk69+/sP6teq6AX54qPBWwQ7aV5ZVdpgb5G64PkY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=NCQS7InN; 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="NCQS7InN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C533DC19425; Mon, 20 Apr 2026 15:56:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776700566; bh=jWeBgu6Il0RwgxJt3SnjG5DkiWdpc6D5fXK398/u1KY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NCQS7InNdUtdFUbdFMq6IZ033Zkt3IsuZyr+/K+ael+XpQsT2dWIxWCYgKFvyrNB7 f2H5iVna8a/gYda3nzmX2hcz41NzyT6Vgr+IPRPHVojl5ALTujSquVezmkkYau69FU HeXkNw65C7kYER2ZeImJxTym6MvkZS77IbKlXi6Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+47321e8fd5a4c84088db@syzkaller.appspotmail.com, Jeongjun Park , Hans Verkuil Subject: [PATCH 6.19 214/220] media: as102: fix to not free memory after the device is registered in as102_usb_probe() Date: Mon, 20 Apr 2026 17:42:35 +0200 Message-ID: <20260420153941.732240065@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260420153934.013228280@linuxfoundation.org> References: <20260420153934.013228280@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeongjun Park commit 8bd29dbe03fc5b0f039ab2395ff37b64236d2f0c upstream. In as102_usb driver, the following race condition occurs: ``` CPU0 CPU1 as102_usb_probe() kzalloc(); // alloc as102_dev_t .... usb_register_dev(); fd = sys_open("/path/to/dev"); // open as102 fd .... usb_deregister_dev(); .... kfree(); // free as102_dev_t .... sys_close(fd); as102_release() // UAF!! as102_usb_release() kfree(); // DFB!! ``` When a USB character device registered with usb_register_dev() is later unregistered (via usb_deregister_dev() or disconnect), the device node is removed so new open() calls fail. However, file descriptors that are already open do not go away immediately: they remain valid until the last reference is dropped and the driver's .release() is invoked. In as102, as102_usb_probe() calls usb_register_dev() and then, on an error path, does usb_deregister_dev() and frees as102_dev_t right away. If userspace raced a successful open() before the deregistration, that open FD will later hit as102_release() --> as102_usb_release() and access or free as102_dev_t again, occur a race to use-after-free and double-free vuln. The fix is to never kfree(as102_dev_t) directly once usb_register_dev() has succeeded. After deregistration, defer freeing memory to .release(). In other words, let release() perform the last kfree when the final open FD is closed. Cc: Reported-by: syzbot+47321e8fd5a4c84088db@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=47321e8fd5a4c84088db Fixes: cd19f7d3e39b ("[media] as102: fix leaks at failure paths in as102_usb_probe()") Signed-off-by: Jeongjun Park Signed-off-by: Hans Verkuil Signed-off-by: Greg Kroah-Hartman --- drivers/media/usb/as102/as102_usb_drv.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/media/usb/as102/as102_usb_drv.c +++ b/drivers/media/usb/as102/as102_usb_drv.c @@ -403,7 +403,9 @@ static int as102_usb_probe(struct usb_in failed_dvb: as102_free_usb_stream_buffer(as102_dev); failed_stream: + usb_set_intfdata(intf, NULL); usb_deregister_dev(intf, &as102_usb_class_driver); + return ret; failed: usb_put_dev(as102_dev->bus_adap.usb_dev); usb_set_intfdata(intf, NULL);