Re: [PATCH 1/2] bpf: btf: silence uninitialize variable warnings

[Martin KaFai Lau]

On Fri, Apr 27, 2018 at 05:04:09PM +0300, Dan Carpenter wrote:
> Smatch complains that size can be uninitialized if btf_type_id_size()
> returns NULL.  It seems reasonable enough to check for that.
> 
> Signed-off-by: Dan Carpenter 
> ---
> This goes to the BPF tree (linux-next).
> 
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 22e1046a1a86..e631b6fd60d3 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -1229,7 +1229,8 @@ static int btf_array_check_member(struct 
> btf_verifier_env *env,
>   }
>  
>   array_type_id = member->type;
> - btf_type_id_size(btf, _type_id, _size);
> + if (!btf_type_id_size(btf, _type_id, _size))
> + return -EINVAL;
This check is not needed.  It does not happen for array.

>   struct_size = struct_type->size;
>   bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
>   if (struct_size - bytes_offset < array_size) {
> @@ -1351,6 +1352,8 @@ static void btf_array_seq_show(const struct btf *btf, 
> const struct btf_type *t,
>  
>   elem_type_id = array->type;
>   elem_type = btf_type_id_size(btf, _type_id, _size);
> + if (!elem_type)
> + return;
This case has already been checked in verification phase.  No need
to recheck everything again..

>   elem_ops = btf_type_ops(elem_type);
>   seq_puts(m, "[");
>   for (i = 0; i < array->nelems; i++) {

[PATCH 1/2] bpf: btf: silence uninitialize variable warnings

[Dan Carpenter]

Smatch complains that size can be uninitialized if btf_type_id_size()
returns NULL.  It seems reasonable enough to check for that.

Signed-off-by: Dan Carpenter 
---
This goes to the BPF tree (linux-next).

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 22e1046a1a86..e631b6fd60d3 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1229,7 +1229,8 @@ static int btf_array_check_member(struct btf_verifier_env 
*env,
}
 
array_type_id = member->type;
-   btf_type_id_size(btf, _type_id, _size);
+   if (!btf_type_id_size(btf, _type_id, _size))
+   return -EINVAL;
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < array_size) {
@@ -1351,6 +1352,8 @@ static void btf_array_seq_show(const struct btf *btf, 
const struct btf_type *t,
 
elem_type_id = array->type;
elem_type = btf_type_id_size(btf, _type_id, _size);
+   if (!elem_type)
+   return;
elem_ops = btf_type_ops(elem_type);
seq_puts(m, "[");
for (i = 0; i < array->nelems; i++) {