CVE-2026-23383

About vulnerability

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. A flaw was found in the Linux kernel’s BPF (Berkeley Packet Filter) JIT (Just-In-Time) compiler on arm64 architectures. The BPF JIT allocator incorrectly requests a 4-byte alignment for its buffer, while a critical target field within the bpf_plt structure requires 8-byte alignment. This misalignment can lead to a “torn read” when the target field is updated concurrently, causing the JIT to jump to a corrupted memory address. An attacker could potentially exploit this vulnerability to achieve arbitrary code execution.

Live-patch status from KernelCare for each operating system.