diff options
| author | Feng Jiang <jiangfeng@kylinos.cn> | 2026-07-20 06:42:57 +0000 |
|---|---|---|
| committer | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2026-07-21 20:23:54 +0200 |
| commit | 5eb8921371c6fd117d4a328b6053dfda38707df8 (patch) | |
| tree | 2b4669b754cd39501288af62d3f8341dfed595eb | |
| parent | 2f2223a993aef8be52a029e15aa56f9ac924cf3e (diff) | |
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.
Fixes: fb7cefabae81 ("riscv, bpf: Add support arena atomics for RV64")
Suggested-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20260720-bpf-riscv-fix-extable-v4-1-165c0b3b07d5@kylinos.cn
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp64.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c index 823262ca47eb..ad089a9a4ea9 100644 --- a/arch/riscv/net/bpf_jit_comp64.c +++ b/arch/riscv/net/bpf_jit_comp64.c @@ -1986,7 +1986,12 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, else ret = emit_atomic_rmw(rd, rs, insn, ctx); - ret = ret ?: add_exception_handler(insn, REG_DONT_CLEAR_MARKER, ctx); + /* ret can be 1 (skip-zext); extable entry still needs to be added */ + if (ret >= 0) + ret = add_exception_handler(insn, + insn->imm == BPF_LOAD_ACQ ? rd : REG_DONT_CLEAR_MARKER, + ctx) ?: ret; + if (ret) return ret; break; |