bpf, riscv: Fix extable handling for arena load_acquire

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In the Linux kernel, the following vulnerability has been resolved: bpf, riscv: Fix extable handling for arena load_acquire emit_atomic_ld_st() returns 1 to have build_body() skip the zext after a sub-word load_acquire. The caller does "ret = ret ?: add_exception_handler(...)", which skips add_exception_handler() on any non-zero ret, so the extable entry is missing and a faulting PROBE_ATOMIC load_acquire oopses. REG_DONT_CLEAR_MARKER leaves rd stale on fault, and the verifier still thinks the load overwrote it, so a program can leak it through a map. Check ret >= 0 before calling add_exception_handler(), and pass rd for LOAD_ACQ so the fault zeroes rd like a PROBE_MEM load. Return ret unchanged for the zext skip.

Source published

17 Sep 2026 16:10:25 UTC

Source modified

19 Oct 2026 09:04:23 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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