Linux CVE-2025-71270

The LoongArch CPU architecture uses ADEM (Address Error Memory) exceptions to signal memory access violations. The Linux kernel implements a BPF exception handling mechanism (EX_TYPE_BPF) that generates fixup entries during BPF JIT compilation to gracefully handle memory access faults from BPF_PROBE_MEM* instructions—a feature intended to allow safe speculative memory reads in eBPF programs. However, the architecture-specific trap handler (do_ade function) was not configured to invoke the common BPF exception recovery routine, leaving JIT-compiled BPF programs unable to recover from ADEM exceptions. This is a missing integration point between the LoongArch exception handling layer and the kernel's cross-architecture BPF exception framework, not a fundamental algorithmic flaw. The root cause relates to incomplete implementation of exception recovery semantics rather than a memory safety or access control bypass.