CVE-2024-47728 Information

Description

In the Linux kernel the following vulnerability has been resolved:

bpf: Zero former ARG_PTR_TO_LONGINT args in case of error

For all non-tracing helpers which formerly had ARG_PTR_TO_LONGINT as input arguments zero the value for the case of an error as otherwise it could leak memory. For tracing it is not needed given CAP_PERFMON can already read all kernel memory anyway hence bpf_get_func_arg() and bpf_get_func_ret() is skipped in here.

Also the MTU helpers mtu_len pointer value is being written but also read. Technically the MEM_UNINIT should not be there in order to always force init. Removing MEM_UNINIT needs more verifier rework though: MEM_UNINIT right now implies two things actually: i) write into memory ii) memory does not have to be initialized. If we lift MEM_UNINIT it then becomes: i) read into memory ii) memory must be initialized. This means that for bpf__check_mtu() we’re readding the issue we’re trying to fix that is it would then be able to write back into things like .rodata BPF maps. Follow-up work will rework the MEM_UNINIT semantics such that the intent can be better expressed. For now just clear the mtu_len on error path which can be lifted later again.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Reference

https://git.kernel.org/stable/c/8397bf78988f3ae9dbebb0200189a62a57264980 https://git.kernel.org/stable/c/a634fa8e480ac2423f86311a602f6295df2c8ed0 https://git.kernel.org/stable/c/599d15b6d03356a97bff7a76155c5604c42a2962 https://git.kernel.org/stable/c/594a9f5a8d2de2573a856e506f77ba7dd2cefc6a https://git.kernel.org/stable/c/4b3786a6c5397dc220b1483d8e2f4867743e966f

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

5.5