[PATCH v2 bpf-next 02/10] bpf: mark relevant stack slots scratched for register read instructions

[Andrii Nakryiko <andrii@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 kernel/bpf/verifier.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ff4a8ab99f08..da8a5834f2ca 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;
 
-- 
2.34.1