An issue was discovered in the Linux kernel before 5.19. In pxa3xx_gcu_write in drivers/video/fbdev/pxa3xx-gcu.c, the count parameter has a type conflict of size_t versus int, causing an integer overflow and bypassing the size check. After that, because it is used as the third argument to copy_from_user(), a heap overflow may occur. NOTE: the original discoverer disputes that the overflow can actually happen.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:NI:LA:H6.1/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H