CVE-2021-3444

The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.

The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.

El comprobador bpf en el kernel de Linux no manejó apropiadamente el truncamiento del registro de destino mod32 cuando se sabía que el registro de origen era 0. Un atacante local con la habilidad de cargar programas bpf podría usar esta ganancia para lecturas fuera de límites en la memoria del kernel que conllevan a una divulgación de información (memoria del kernel) y, posiblemente, escrituras fuera de límites que podrían conllevar a una ejecución de código. Este problema se solucionó en el kernel ascendente en el commit 9b00f1b78809 ("bpf: Fix truncation handling for mod32 dst reg wrt zero") y en los kernels estables de Linux versiones 5.11.2, 5.10.19 y 5.4.101