CVE-2021-33655

Cuando son enviados datos maliciosos al kernel mediante ioctl cmd FBIOPUT_VSCREENINFO, el kernel escribirá memoria fuera de límites

An out-of-bounds write flaw was found in the Linux kernel’s framebuffer-based console driver functionality in the way a user triggers ioctl FBIOPUT_VSCREENINFO with malicious data. This flaw allows a local user to crash or potentially escalate their privileges on the system.

It was discovered that the framebuffer driver on the Linux kernel did not verify size limits when changing font or screen size, leading to an out-of- bounds write. A local attacker could use this to cause a denial of service or possibly execute arbitrary code. Domingo Dirutigliano and Nicola Guerrera discovered that the netfilter subsystem in the Linux kernel did not properly handle rules that truncated packets below the packet header size. When such rules are in place, a remote attacker could possibly use this to cause a denial of service.