CVE-2025-38339 powerpc/bpf: fix JIT code size calculation of bpf trampoline
Incorrect JIT code size calculation in the Linux kernel BPF trampoline can cause a kernel warning and potential denial of service.
- 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-2025-38339?
CVE-2025-38339 is a high-severity vulnerability in Linux kernel, published on 10 Jul 2025. 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:
powerpc/bpf: fix JIT code size calculation of bpf trampoline
arch_bpf_trampoline_size() provides JIT size of the BPF trampoline before the buffer for JIT'ing it is allocated. The total number of instructions emitted for BPF trampoline JIT code depends on where the final image is located. So, the size arrived at with the dummy pass in arch_bpf_trampoline_size() can vary from the actual size needed in arch_prepare_bpf_trampoline(). When the instructions accounted in arch_bpf_trampoline_size() is less than the number of instructions emitted during the actual JIT compile of the trampoline, the below warning is produced:
WARNING: CPU: 8 PID: 204190 at arch/powerpc/net/bpf_jit_comp.c:981 __arch_prepare_bpf_trampoline.isra.0+0xd2c/0xdcc
which is:
/* Make sure the trampoline generation logic doesn't overflow */ if (image && WARN_ON_ONCE(&image[ctx->idx] > (u32 *)rw_image_end - BPF_INSN_SAFETY)) {
So, during the dummy pass, instead of providing some arbitrary image location, account for maximum possible instructions if and when there is a dependency with image location for JIT'ing.
Which versions are affected by CVE-2025-38339?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38339?
Apply the vendor's patch.
Is CVE-2025-38339 being exploited?
There is no known exploitation of CVE-2025-38339 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38339, GHSA-pcqg-8r4j-p55f, UBUNTU-CVE-2025-38339.