This is made to clarify that this flag will cause a nospec to be added after this insn and can therefore be relied upon to reduce speculative path analysis.
Signed-off-by: Luis Gerhorst luis.gerhorst@fau.de Cc: Henriette Herzog henriette.herzog@rub.de Cc: Maximilian Ott ott@cs.fau.de Cc: Milan Stephan milan.stephan@fau.de --- include/linux/bpf_verifier.h | 2 +- kernel/bpf/verifier.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 9734544b6957..cebb67becdad 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -576,7 +576,7 @@ struct bpf_insn_aux_data { u64 map_key_state; /* constant (32 bit) key tracking for maps */ int ctx_field_size; /* the ctx field size for load insn, maybe 0 */ u32 seen; /* this insn was processed by the verifier at env->pass_cnt */ - bool sanitize_stack_spill; /* subject to Spectre v4 sanitation */ + bool nospec_result; /* result is unsafe under speculation, nospec must follow */ bool zext_dst; /* this insn zero extends dst reg */ bool needs_zext; /* alu op needs to clear upper bits */ bool storage_get_func_atomic; /* bpf_*_storage_get() with atomic memory alloc */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 27d3bc97a9e0..3d446c19bdf6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5031,7 +5031,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, }
if (sanitize) - env->insn_aux_data[insn_idx].sanitize_stack_spill = true; + env->insn_aux_data[insn_idx].nospec_result = true; }
err = destroy_if_dynptr_stack_slot(env, state, spi); @@ -20886,7 +20886,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) }
if (type == BPF_WRITE && - env->insn_aux_data[i + delta].sanitize_stack_spill) { + env->insn_aux_data[i + delta].nospec_result) { struct bpf_insn patch[] = { *insn, BPF_ST_NOSPEC(),