Commit 1057d299 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

bpf: Teach the verifier to recognize rdonly_mem as not null. 



Teach the verifier to recognize PTR_TO_MEM | MEM_RDONLY as not NULL
otherwise if (!bpf_ksym_exists(known_kfunc)) doesn't go through
dead code elimination.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230321203854.3035-3-alexei.starovoitov@gmail.com
parent a18f7214

kernel/bpf/verifier.c

+9 −5
Original line number Diff line number Diff line
@@ -486,8 +486,17 @@ static bool type_is_sk_pointer(enum bpf_reg_type type) 
		type == PTR_TO_XDP_SOCK;

}









static bool type_may_be_null(u32 type)









{









	return type & PTR_MAYBE_NULL;









}

















static bool reg_type_not_null(enum bpf_reg_type type)









{









	if (type_may_be_null(type))









		return false;

















	type = base_type(type);









	return type == PTR_TO_SOCKET ||









		type == PTR_TO_TCP_SOCK ||









		type == PTR_TO_MAP_VALUE ||








@@ -531,11 +540,6 @@ static bool type_is_rdonly_mem(u32 type)







	return type & MEM_RDONLY;









}

















static bool type_may_be_null(u32 type)









{









	return type & PTR_MAYBE_NULL;









}

















static bool is_acquire_function(enum bpf_func_id func_id,









				const struct bpf_map *map)









{