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

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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: Yongqiang Liu liuyongqiang13@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 22b606af0a87..2256e5816090 100644 --- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -140,6 +140,8 @@ 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) { @@ -1073,9 +1075,13 @@ 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++;

@@ -1099,6 +1105,8 @@ 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; }

@@ -1747,6 +1755,8 @@ 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"); @@ -1767,6 +1777,8 @@ 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 = {