Commit 0789e13b authored by Lorenz Bauer's avatar Lorenz Bauer Committed by Alexei Starovoitov
Browse files

bpf: Explicitly size compatible_reg_types 



Arrays with designated initializers have an implicit length of the highest
initialized value plus one. I used this to ensure that newly added entries
in enum bpf_reg_type get a NULL entry in compatible_reg_types.

This is difficult to understand since it requires knowledge of the
peculiarities of designated initializers. Use __BPF_ARG_TYPE_MAX to size
the array instead.

Suggested-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarLorenz Bauer <lmb@cloudflare.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200923160156.80814-1-lmb@cloudflare.com
parent a8a71796

kernel/bpf/verifier.c

+1 −2
Original line number Diff line number Diff line
@@ -4002,7 +4002,7 @@ static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_T 
static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };

static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };



static const struct bpf_reg_types *compatible_reg_types[] = {

static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {

	[ARG_PTR_TO_MAP_KEY]		= &map_key_value_types,

	[ARG_PTR_TO_MAP_VALUE]		= &map_key_value_types,

	[ARG_PTR_TO_UNINIT_MAP_VALUE]	= &map_key_value_types,
@@ -4025,7 +4025,6 @@ static const struct bpf_reg_types *compatible_reg_types[] = { 
	[ARG_PTR_TO_ALLOC_MEM_OR_NULL]	= &alloc_mem_types,

	[ARG_PTR_TO_INT]		= &int_ptr_types,

	[ARG_PTR_TO_LONG]		= &int_ptr_types,

	[__BPF_ARG_TYPE_MAX]		= NULL,

};



static int check_reg_type(struct bpf_verifier_env *env, u32 regno,