From 482d548d40b0af9af730e4869903d4433e44f014 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 8 Dec 2023 17:09:57 -0800 Subject: bpf: handle fake register spill to stack with BPF_ST_MEM instruction When verifier validates BPF_ST_MEM instruction that stores known constant to stack (e.g., *(u64 *)(r10 - 8) = 123), it effectively spills a fake register with a constant (but initially imprecise) value to a stack slot. Because read-side logic treats it as a proper register fill from stack slot, we need to mark such stack slot initialization as INSN_F_STACK_ACCESS instruction to stop precision backtracking from missing it. Fixes: 41f6f64e6999 ("bpf: support non-r10 register spill/fill to/from stack in precision tracking") Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20231209010958.66758-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel/bpf') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fb690539d5f6..727a59e4a647 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4498,7 +4498,6 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, __mark_reg_known(&fake_reg, insn->imm); fake_reg.type = SCALAR_VALUE; save_register_state(env, state, spi, &fake_reg, size); - insn_flags = 0; /* not a register spill */ } else if (reg && is_spillable_regtype(reg->type)) { /* register containing pointer is being spilled into stack */ if (size != BPF_REG_SIZE) { -- cgit v1.2.3