From: Hyunwoo Kim <imv4bel@gmail.com> mainline inclusion from mainline-v6.0-rc1 commit 5610bcfe8693c02e2e4c8b31427f1bdbdecc839c category: bugfix bugzilla: 187798, https://gitee.com/src-openeuler/kernel/issues/I5U1NZ CVE: CVE-2022-41849 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs... --------------------------- A race condition may occur if the user physically removes the USB device while calling open() for this device node. This is a race condition between the ufx_ops_open() function and the ufx_usb_disconnect() function, which may eventually result in UAF. So, add a mutex to the ufx_ops_open() and ufx_usb_disconnect() functions to avoid race contidion of krefs. Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- drivers/video/fbdev/smscufx.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx.c index 28768c272b73..7673db5da26b 100644 --- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -137,6 +137,8 @@ static int ufx_submit_urb(struct ufx_data *dev, struct urb * urb, size_t len); static int ufx_alloc_urb_list(struct ufx_data *dev, int count, size_t size); static void ufx_free_urb_list(struct ufx_data *dev); +static DEFINE_MUTEX(disconnect_mutex); + /* reads a control register */ static int ufx_reg_read(struct ufx_data *dev, u32 index, u32 *data) { @@ -1070,9 +1072,13 @@ static int ufx_ops_open(struct fb_info *info, int user) if (user == 0 && !console) return -EBUSY; + mutex_lock(&disconnect_mutex); + /* If the USB device is gone, we don't accept new opens */ - if (dev->virtualized) + if (dev->virtualized) { + mutex_unlock(&disconnect_mutex); return -ENODEV; + } dev->fb_count++; @@ -1096,6 +1102,8 @@ static int ufx_ops_open(struct fb_info *info, int user) pr_debug("open /dev/fb%d user=%d fb_info=%p count=%d", info->node, user, info, dev->fb_count); + mutex_unlock(&disconnect_mutex); + return 0; } @@ -1740,6 +1748,8 @@ static void ufx_usb_disconnect(struct usb_interface *interface) { struct ufx_data *dev; + mutex_lock(&disconnect_mutex); + dev = usb_get_intfdata(interface); pr_debug("USB disconnect starting\n"); @@ -1760,6 +1770,8 @@ static void ufx_usb_disconnect(struct usb_interface *interface) kref_put(&dev->kref, ufx_free); /* consider ufx_data freed */ + + mutex_unlock(&disconnect_mutex); } static struct usb_driver ufx_driver = { -- 2.20.1