Commit 9124a450 authored by Luis Gerhorst's avatar Luis Gerhorst Committed by Alexei Starovoitov
Browse files

bpf: Rename sanitize_stack_spill to nospec_result 



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: default avatarLuis Gerhorst <luis.gerhorst@fau.de>
Acked-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Henriette Herzog <henriette.herzog@rub.de>
Cc: Maximilian Ott <ott@cs.fau.de>
Cc: Milan Stephan <milan.stephan@fau.de>
Link: https://lore.kernel.org/r/20250603212024.338154-1-luis.gerhorst@fau.de


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent dff883d9

include/linux/bpf_verifier.h

+1 −1
Original line number Diff line number Diff line
@@ -580,7 +580,7 @@ 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 */

kernel/bpf/verifier.c

+2 −2
Original line number Diff line number Diff line
@@ -5027,7 +5027,7 @@ 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);








@@ -20930,7 +20930,7 @@ 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(),