From a2bbe7cc90755283f1db719eb757616cefd2a9fd Mon Sep 17 00:00:00 2001 From: Lorenz Bauer Date: Mon, 21 Sep 2020 13:12:24 +0100 Subject: [PATCH] bpf: Set meta->raw_mode for pointers close to use If we encounter a pointer to memory, we set meta->raw_mode depending on the type of memory we point at. What isn't obvious is that this information is only used when the next memory size argument is encountered. Move the assignment closer to where it's used, and add a comment that explains what is going on. Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200921121227.255763-9-lmb@cloudflare.com --- kernel/bpf/verifier.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fc795ba..446fbe7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4067,7 +4067,6 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, type != PTR_TO_RDWR_BUF && type != expected_type) goto err_type; - meta->raw_mode = arg_type == ARG_PTR_TO_UNINIT_MEM; } else if (arg_type_is_alloc_mem_ptr(arg_type)) { expected_type = PTR_TO_MEM; if (register_is_null(reg) && @@ -4156,6 +4155,11 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, err = check_helper_mem_access(env, regno, meta->map_ptr->value_size, false, meta); + } else if (arg_type_is_mem_ptr(arg_type)) { + /* The access to this pointer is only checked when we hit the + * next is_mem_size argument below. + */ + meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM); } else if (arg_type_is_mem_size(arg_type)) { bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO); -- 2.7.4