Re: [PATCH 07/46] selinux: Delete unnecessary variable assignments in policydb_index()

Casey Schaufler
2017-01-17T16:31:09Z

On 1/15/2017 7:04 AM, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Sat, 14 Jan 2017 13:40:25 +0100
>
> The local variable "rc" was reset with an error code up to five times
> before a memory allocation failure was detected.
>
> Add a jump target so that this assignment will only be performed after
> a concrete software failure.
>
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>

Of course the maintainers get the call on this,
but I see this as an example of the kind of code
that led to the "gotos considered harmful" mindset.
What value does it add? All I see is unnecessary
code churn. And a backwards goto.

> ---
> security/selinux/ss/policydb.c | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
> index 21869b622c0c..4d4ba1ad910d 100644
> --- a/security/selinux/ss/policydb.c
> +++ b/security/selinux/ss/policydb.c
> @@ -539,34 +539,30 @@ static int policydb_index(struct policydb *p)
> symtab_hash_eval(p->symtab);
> #endif
>
> - rc = -ENOMEM;
> p->class_val_to_struct = kcalloc(p->p_classes.nprim,
> sizeof(*p->class_val_to_struct),
> GFP_KERNEL);
> if (!p->class_val_to_struct)
> - goto out;
> + goto failure_indication;
>
> - rc = -ENOMEM;
> p->role_val_to_struct = kcalloc(p->p_roles.nprim,
> sizeof(*p->role_val_to_struct),
> GFP_KERNEL);
> if (!p->role_val_to_struct)
> - goto out;
> + goto failure_indication;
>
> - rc = -ENOMEM;
> p->user_val_to_struct = kcalloc(p->p_users.nprim,
> sizeof(*p->user_val_to_struct),
> GFP_KERNEL);
> if (!p->user_val_to_struct)
> - goto out;
> + goto failure_indication;
>
> /* Yes, I want the sizeof the pointer, not the structure */
> - rc = -ENOMEM;
> p->type_val_to_struct_array = flex_array_alloc(sizeof(struct type_datum *),
> p->p_types.nprim,
> GFP_KERNEL | __GFP_ZERO);
> if (!p->type_val_to_struct_array)
> - goto out;
> + goto failure_indication;
>
> rc = flex_array_prealloc(p->type_val_to_struct_array, 0,
> p->p_types.nprim, GFP_KERNEL | __GFP_ZERO);
> @@ -578,12 +574,11 @@ static int policydb_index(struct policydb *p)
> goto out;
>
> for (i = 0; i < SYM_NUM; i++) {
> - rc = -ENOMEM;
> p->sym_val_to_name[i] = flex_array_alloc(sizeof(char *),
> p->symtab[i].nprim,
> GFP_KERNEL | __GFP_ZERO);
> if (!p->sym_val_to_name[i])
> - goto out;
> + goto failure_indication;
>
> rc = flex_array_prealloc(p->sym_val_to_name[i],
> 0, p->symtab[i].nprim,
> @@ -598,6 +593,9 @@ static int policydb_index(struct policydb *p)
> rc = 0;
> out:
> return rc;
> +failure_indication:
> + rc = -ENOMEM;
> + goto out;
> }
>
> /*