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

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

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

In the function arkfb_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:

[ 659.399066] BUG: unable to handle page fault for address: ffffc90003000000 [ 659.399077] #PF: supervisor write access in kernel mode [ 659.399079] #PF: error_code(0x0002) - not-present page [ 659.399094] RIP: 0010:memset_orig+0x33/0xb0 [ 659.399116] Call Trace: [ 659.399122] arkfb_set_par+0x143f/0x24c0 [ 659.399130] fb_set_var+0x604/0xeb0 [ 659.399161] do_fb_ioctl+0x234/0x670 [ 659.399189] fb_ioctl+0xdd/0x130

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