From: Andrii Nakryiko <andrii@kernel.org>
Date: Fri, 5 May 2023 04:33:09 +0000 (-0700)
Subject: bpf: mark relevant stack slots scratched for register read instructions
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e0bf462276b6ee23203365eacb5c599f42a5a084;p=linux.git

bpf: mark relevant stack slots scratched for register read instructions

When handling instructions that read register slots, mark relevant stack
slots as scratched so that verifier log would contain those slots' states, in
addition to currently emitted registers with stack slot offsets.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230505043317.3629845-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ff4a8ab99f08c..da8a5834f2ca4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4109,6 +4109,7 @@ static void mark_reg_stack_read(struct bpf_verifier_env *env,
 	for (i = min_off; i < max_off; i++) {
 		slot = -i - 1;
 		spi = slot / BPF_REG_SIZE;
+		mark_stack_slot_scratched(env, spi);
 		stype = ptr_state->stack[spi].slot_type;
 		if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
 			break;
@@ -4160,6 +4161,8 @@ static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
 	stype = reg_state->stack[spi].slot_type;
 	reg = &reg_state->stack[spi].spilled_ptr;
 
+	mark_stack_slot_scratched(env, spi);
+
 	if (is_spilled_reg(&reg_state->stack[spi])) {
 		u8 spill_size = 1;