Wind River Support Network

Description

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.