Hi

Am 14.10.21 um 15:22 schrieb Wang Hai:

I got a null-ptr-deref report:

BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:fb_destroy_modelist+0x38/0x100 ... Call Trace: ufx_usb_probe.cold+0x2b5/0xac1 [smscufx] usb_probe_interface+0x1aa/0x3c0 [usbcore] really_probe+0x167/0x460 ... ret_from_fork+0x1f/0x30

If fb_alloc_cmap() fails in ufx_usb_probe(), fb_destroy_modelist() will be called to destroy modelist in the error handling path. But modelist has not been initialized yet, so it will result in null-ptr-deref.

Initialize modelist before calling fb_alloc_cmap() to fix this bug.

Fixes: 3c8a63e22a08 ("Add support for SMSC UFX6000/7000 USB display adapters") Reported-by: Hulk Robot hulkci@huawei.com Signed-off-by: Wang Hai wanghai38@huawei.com

Acked-by: Thomas Zimmermann tzimmermann@suse.de

I got one of these devices but the driver didn't produce any output for me. Are actually able to use the driver?

Best regards Thomas

---

drivers/video/fbdev/smscufx.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx.c index bfac3ee4a642..28768c272b73 100644 --- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -1656,6 +1656,7 @@ static int ufx_usb_probe(struct usb_interface *interface, info->par = dev; info->pseudo_palette = dev->pseudo_palette; info->fbops = &ufx_ops;

• INIT_LIST_HEAD(&info->modelist);

  retval = fb_alloc_cmap(&info->cmap, 256, 0); if (retval < 0) {

@@ -1666,8 +1667,6 @@ static int ufx_usb_probe(struct usb_interface *interface, INIT_DELAYED_WORK(&dev->free_framebuffer_work, ufx_free_framebuffer_work);

• INIT_LIST_HEAD(&info->modelist);
• retval = ufx_reg_read(dev, 0x3000, &id_rev); check_warn_goto_error(retval, "error %d reading 0x3000 register from device", retval); dev_dbg(dev->gdev, "ID_REV register value 0x%08x", id_rev);