CVE-2024-47728 bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
An attacker with BPF access can read uninitialized kernel memory via specific helper functions, potentially exposing sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-47728?
CVE-2024-47728 is a medium-severity vulnerability in Linux kernel, published on 21 Oct 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
For all non-tracing helpers which formerly had ARG_PTR_TO_{LONG,INT} 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.
Weakness: CWE-459
Which versions are affected by CVE-2024-47728?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-47728?
Apply the vendor's patch.
Is CVE-2024-47728 being exploited?
There is no known exploitation of CVE-2024-47728 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-50703, AZL-50972, BELL-CVE-2024-47728, DEBIAN-CVE-2024-47728, GHSA-8vqp-74w3-mg32, ROOT-OS-DEBIAN-11-CVE-2024-47728 and 2 more.