UPSTREAM: 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.

Change-Id: I193c3686051efe82b61806ca50055b8eadc113b6
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-9-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer 2020-09-21 13:12:24 +01:00 • committed by basamaryan
commit 247debe7aa
No known key found for this signature in database
GPG key ID: 210D5384FB2A5885

View file

@ -4065,7 +4065,6 @@ 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) &&
@ -4154,6 +4153,11 @@ 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);