CVE-2025-38233 powerpc64/ftrace: fix clobbered r15 during livepatching
A kernel bug in powerpc64 ftrace livepatching fails to restore register r15, causing memory corruption and system crashes.
- 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-2025-38233?
CVE-2025-38233 is a high-severity memory corruption vulnerability in Linux kernel, published on 4 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:
powerpc64/ftrace: fix clobbered r15 during livepatching
While r15 is clobbered always with PPC_FTRACE_OUT_OF_LINE, it is not restored in livepatch sequence leading to not so obvious fails like below:
BUG: Unable to handle kernel data access on write at 0xc0000000000f9078 Faulting instruction address: 0xc0000000018ff958 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP: c0000000018ff958 LR: c0000000018ff930 CTR: c0000000009c0790 REGS: c00000005f2e7790 TRAP: 0300 Tainted: G K (6.14.0+) MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 2822880b XER: 20040000 CFAR: c0000000008addc0 DAR: c0000000000f9078 DSISR: 0a000000 IRQMASK: 1 GPR00: c0000000018f2584 c00000005f2e7a30 c00000000280a900 c000000017ffa488 GPR04: 0000000000000008 0000000000000000 c0000000018f24fc 000000000000000d GPR08: fffffffffffe0000 000000000000000d 0000000000000000 0000000000008000 GPR12: c0000000009c0790 c000000017ffa480 c00000005f2e7c78 c0000000000f9070 GPR16: c00000005f2e7c90 0000000000000000 0000000000000000 0000000000000000 GPR20: 0000000000000000 c00000005f3efa80 c00000005f2e7c60 c00000005f2e7c88 GPR24: c00000005f2e7c60 0000000000000001 c0000000000f9078 0000000000000000 GPR28: 00007fff97960000 c000000017ffa480 0000000000000000 c0000000000f9078 ... Call Trace: check_heap_object+0x34/0x390 (unreliable) __mutex_unlock_slowpath.isra.0+0xe4/0x230 seq_read_iter+0x430/0xa90 proc_reg_read_iter+0xa4/0x200 vfs_read+0x41c/0x510 ksys_read+0xa4/0x190 system_call_exception+0x1d0/0x440 system_call_vectored_common+0x15c/0x2ec
Fix it by restoring r15 always.
Which versions are affected by CVE-2025-38233?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38233?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-38233 being exploited?
There is no known exploitation of CVE-2025-38233 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38233, GHSA-mfmj-296r-5fqr, UBUNTU-CVE-2025-38233.