From 6f401e350939442b2ac905f7e5ac952e3802a5d8 Mon Sep 17 00:00:00 2001 From: Yizhou Zhao Date: Sun, 7 Jun 2026 21:01:16 +0800 Subject: [PATCH] net/9p/usbg: Fix use-after-free in disable_usb9pfs() disable_usb9pfs() frees the IN and OUT usb_request objects before it disables the corresponding endpoints. If either request is still queued, the later usb_ep_disable() call cancels the endpoint queue and the UDC driver can still access the already freed request. With dummy_hcd and KASAN, this is reproducible by queueing the OUT request and then disconnecting the configfs gadget: BUG: KASAN: slab-use-after-free in dummy_disable+0x2b4/0x300 Read of size 8 at addr ffff888009702400 by task sh/1 usb_ep_disable+0x8e/0x1f0 usb9pfs_func_unbind+0x193/0x350 gadget_dev_desc_UDC_store+0x135/0x280 dummy_free_request() also warns because the request is freed while its queue entry is still linked. Disable both endpoints before freeing the request objects. This lets usb_ep_disable() cancel any queued transfers and invoke the completion callback while the request storage is still valid. The request objects are then freed only after they have been removed from the endpoint queues. Fixes: a3be076dc174 ("net/9p/usbg: Add new usb gadget function transport") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao Reported-by: Yuxiang Yang Reported-by: Ao Wang Reported-by: Xuewei Feng Reported-by: Qi Li Reported-by: Ke Xu Assisted-by: GLM:GLM-5.1 Signed-off-by: Yizhou Zhao Acked-by: Michael Grzeschik Message-ID: <20260607130118.16579-1-zhaoyz24@mails.tsinghua.edu.cn> Signed-off-by: Dominique Martinet --- net/9p/trans_usbg.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/net/9p/trans_usbg.c b/net/9p/trans_usbg.c index 9fd7801d56ab..f4ff0349166b 100644 --- a/net/9p/trans_usbg.c +++ b/net/9p/trans_usbg.c @@ -278,6 +278,9 @@ static void disable_usb9pfs(struct f_usb9pfs *usb9pfs) struct usb_composite_dev *cdev = usb9pfs->function.config->cdev; + disable_ep(cdev, usb9pfs->in_ep); + disable_ep(cdev, usb9pfs->out_ep); + if (usb9pfs->in_req) { usb_ep_free_request(usb9pfs->in_ep, usb9pfs->in_req); usb9pfs->in_req = NULL; @@ -287,9 +290,6 @@ static void disable_usb9pfs(struct f_usb9pfs *usb9pfs) usb_ep_free_request(usb9pfs->out_ep, usb9pfs->out_req); usb9pfs->out_req = NULL; } - - disable_ep(cdev, usb9pfs->in_ep); - disable_ep(cdev, usb9pfs->out_ep); dev_dbg(&cdev->gadget->dev, "%s disabled\n", usb9pfs->function.name); }