CVE-2024-57877 arm64: ptrace: fix partial SETREGSET for NT_ARM_POE
A local attacker can leak up to 64 bits of kernel stack memory via a zero-length ptrace SETREGSET call on ARM64 systems.
- 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-2024-57877?
CVE-2024-57877 is a medium-severity vulnerability in Linux kernel, published on 11 Jan 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:
arm64: ptrace: fix partial SETREGSET for NT_ARM_POE
Currently poe_set() doesn't initialize the temporary 'ctrl' variable, and a SETREGSET call with a length of zero will leave this uninitialized. Consequently an arbitrary value will be written back to target->thread.por_el0, potentially leaking up to 64 bits of memory from the kernel stack. The read is limited to a specific slot on the stack, and the issue does not provide a write mechanism.
Fix this by initializing the temporary value before copying the regset from userspace, as for other regsets (e.g. NT_PRSTATUS, NT_PRFPREG, NT_ARM_SYSTEM_CALL). In the case of a zero-length write, the existing contents of POR_EL1 will be retained.
Before this patch:
| # ./poe-test | Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d | SETREGSET(nt=0x40f, len=8) wrote 8 bytes | | Attempting to read NT_ARM_POE::por_el0 | GETREGSET(nt=0x40f, len=8) read 8 bytes | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d | | Attempting to write NT_ARM_POE (zero length) | SETREGSET(nt=0x40f, len=0) wrote 0 bytes | | Attempting to read NT_ARM_POE::por_el0 | GETREGSET(nt=0x40f, len=8) read 8 bytes | Read NT_ARM_POE::por_el0 = 0xffff8000839c3d50
After this patch:
| # ./poe-test | Attempting to write NT_ARM_POE::por_el0 = 0x900d900d900d900d | SETREGSET(nt=0x40f, len=8) wrote 8 bytes | | Attempting to read NT_ARM_POE::por_el0 | GETREGSET(nt=0x40f, len=8) read 8 bytes | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d | | Attempting to write NT_ARM_POE (zero length) | SETREGSET(nt=0x40f, len=0) wrote 0 bytes | | Attempting to read NT_ARM_POE::por_el0 | GETREGSET(nt=0x40f, len=8) read 8 bytes | Read NT_ARM_POE::por_el0 = 0x900d900d900d900d
Weakness: CWE-908
Which versions are affected by CVE-2024-57877?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-57877?
Apply the vendor's patch.
Is CVE-2024-57877 being exploited?
There is no known exploitation of CVE-2024-57877 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-57877, DEBIAN-CVE-2024-57877, GHSA-xfvh-9mxf-99vm, UBUNTU-CVE-2024-57877.