From: Wang Hai <wanghai38@huawei.com> stable inclusion from stable-v4.19.238 commit dd3a6cc7385b89ec2303f39dfc3bafa4e24cec4b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBP6B9 CVE: CVE-2021-47652 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 1791f487f877a9e83d81c8677bd3e7b259e7cb27 ] 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> Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- 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 2256e5816090..8d31b0806cb7 100644 --- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -1670,6 +1670,7 @@ 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) { @@ -1680,8 +1681,6 @@ 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); -- 2.25.1