CVE-2022-50101

In the Linux kernel, the following vulnerability has been resolved:

video: fbdev: vt8623fb: Check the size of screen before memset_io()

In the function vt8623fb_set_par(), the value of 'screen_size' is calculated by the user input. If the user provides the improper value, the value of 'screen_size' may larger than 'info->screen_size', which may cause the following bug:

[ 583.339036] BUG: unable to handle page fault for address: ffffc90005000000 [ 583.339049] #PF: supervisor write access in kernel mode [ 583.339052] #PF: error_code(0x0002) - not-present page [ 583.339074] RIP: 0010:memset_orig+0x33/0xb0 [ 583.339110] Call Trace: [ 583.339118] vt8623fb_set_par+0x11cd/0x21e0 [ 583.339146] fb_set_var+0x604/0xeb0 [ 583.339181] do_fb_ioctl+0x234/0x670 [ 583.339209] fb_ioctl+0xdd/0x130

Fix the this by checking the value of 'screen_size' before memset_io().

Red Hat Enterprise Linux is not affected by this vulnerability because the legacy VIA VT8623 framebuffer driver is not enabled in Red Hat supported kernels. This flaw involves improper bounds checking during display parameter configuration, which could allow a local user to cause a kernel crash through an out-of-bounds memory write. Because the associated driver is entirely omitted from shipping enterprise kernel builds, the vulnerable code is not present on Red Hat systems.