bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
Affects the Linux kernel arm64 BPF JIT in 6.0 through 6.6.159, 6.7 through 6.12.76, 6.13 through 6.18.16, and 6.19.0 through 6.19.6. Fixed in 6.6.160, 6.12.77, 6.18.17, and 6.19.7.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 6.6.160, 6.12.77, 6.18.17, 6.19.7
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing struct bpf_plt contains a u64 target field. Currently, the BPF JIT allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT buffer. Because the base address of the JIT buffer can be 4-byte aligned (e.g., ending in 0x4 or 0xc), the relative padding logic in build_plt() fails to ensure that target lands on an 8-byte boundary. This leads to two issues: 1. UBSAN reports misaligned-access warnings when dereferencing the structure. 2. More critically, target is updated concurrently via WRITE_ONCE() in bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64, 64-bit loads/stores are only guaranteed to be single-copy atomic if they are 64-bit aligned. A misaligned target risks a torn read, causing the JIT to jump to a corrupted address. Fix this by increasing the allocation alignment requirement to 8 bytes (sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of the JIT buffer to an 8-byte boundary, allowing the relative padding math in build_plt() to correctly align the target field.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
6.0
- KernelLinux
From 6.0.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.77; From 6.13.0 · fixed in 6.18.17; From 6.19.0 · fixed in 6.19.7
References 6
git.kernel.org
Questions about CVE-2026-23383
What does this mean?
The arm64 BPF JIT buffer can be 4-byte aligned, so a misaligned target field can suffer a torn read. The JIT may then jump to a corrupted address, and UBSAN reports misaligned-access warnings.Source: git.kernel.org
Am I affected, and how do I check?
The affected ranges are Linux kernel 6.0 before 6.6.160, 6.7 before 6.12.77, 6.13 before 6.18.17, and 6.19.0 before 6.19.7, on arm64. To check, run uname -r for the kernel version and uname -m for the architecture, then compare them with these ranges.Source: git.kernel.org
What should I do about it?
Upgrade to the fixed kernel for your branch: 6.6.160, 6.12.77, 6.18.17, or 6.19.7. Use the release that matches your current version line.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data