diff options
| author |   Lorenz Bauer <lmb@cloudflare.com> | 2020-09-21 13:12:18 +0100 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-09-21 15:00:40 -0700 |
| commit | 0d004c020b5574e51f7a525e57d2a11958b334b5 (patch) | |
| tree | af1c170427677e73f706402346add1c61f3046a9 /kernel | |
| parent | btf: Make btf_set_contains take a const pointer (diff) | |
| download | linux-dev-0d004c020b5574e51f7a525e57d2a11958b334b5.tar.xz linux-dev-0d004c020b5574e51f7a525e57d2a11958b334b5.zip | |
bpf: Check scalar or invalid register in check_helper_mem_access
Move the check for a NULL or zero register to check_helper_mem_access. This
makes check_stack_boundary easier to understand.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-3-lmb@cloudflare.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 24 |
1 files changed, 11 insertions, 13 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 4161b6c406bc..06238395f244 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3641,18 +3641,6 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno, struct bpf_func_state *state = func(env, reg); int err, min_off, max_off, i, j, slot, spi; - if (reg->type != PTR_TO_STACK) { - /* Allow zero-byte read from NULL, regardless of pointer type */ - if (zero_size_allowed && access_size == 0 && - register_is_null(reg)) - return 0; - - verbose(env, "R%d type=%s expected=%s\n", regno, - reg_type_str[reg->type], - reg_type_str[PTR_TO_STACK]); - return -EACCES; - } - if (tnum_is_const(reg->var_off)) { min_off = max_off = reg->var_off.value + reg->off; err = __check_stack_boundary(env, regno, min_off, access_size, @@ -3797,9 +3785,19 @@ static int check_helper_mem_access(struct bpf_verifier_env *env, int regno, access_size, zero_size_allowed, "rdwr", &env->prog->aux->max_rdwr_access); - default: /* scalar_value|ptr_to_stack or invalid ptr */ + case PTR_TO_STACK: return check_stack_boundary(env, regno, access_size, zero_size_allowed, meta); + default: /* scalar_value or invalid ptr */ + /* Allow zero-byte read from NULL, regardless of pointer type */ + if (zero_size_allowed && access_size == 0 && + register_is_null(reg)) + return 0; + + verbose(env, "R%d type=%s expected=%s\n", regno, + reg_type_str[reg->type], + reg_type_str[PTR_TO_STACK]); + return -EACCES; } } |