In audit_rule_change(), audit_data_to_entry() is firstly invoked to
translate the payload data to the kernel's rule representation. In
audit_data_to_entry(), depending on the audit field type, an audit tree may
be created in audit_make_tree(), which eventually invokes kmalloc() to
allocate the tree. Since this tree is a temporary tree, it will be then
freed in the following execution, e.g., audit_add_rule() if the message
type is AUDIT_ADD_RULE or audit_del_rule() if the message type is
AUDIT_DEL_RULE. However, if the message type is neither AUDIT_ADD_RULE nor
AUDIT_DEL_RULE, i.e., the default case of the switch statement, this
temporary tree is not freed.
To fix this issue, free the allocated tree in the default case.
Signed-off-by: Wenwen Wang <[email protected]>
---
kernel/auditfilter.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 63f8b3f..70a34db 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1128,6 +1128,8 @@ int audit_rule_change(int type, int seq, void *data, size_t datasz)
audit_log_rule_change("remove_rule", &entry->rule, !err);
break;
default:
+ if (entry->rule.tree)
+ audit_put_tree(entry->rule.tree);
err = -EINVAL;
WARN_ON(1);
}
--
2.7.4
On Thu, Apr 18, 2019 at 1:39 PM Wenwen Wang <[email protected]> wrote:
> In audit_rule_change(), audit_data_to_entry() is firstly invoked to
> translate the payload data to the kernel's rule representation. In
> audit_data_to_entry(), depending on the audit field type, an audit tree may
> be created in audit_make_tree(), which eventually invokes kmalloc() to
> allocate the tree. Since this tree is a temporary tree, it will be then
> freed in the following execution, e.g., audit_add_rule() if the message
> type is AUDIT_ADD_RULE or audit_del_rule() if the message type is
> AUDIT_DEL_RULE. However, if the message type is neither AUDIT_ADD_RULE nor
> AUDIT_DEL_RULE, i.e., the default case of the switch statement, this
> temporary tree is not freed.
>
> To fix this issue, free the allocated tree in the default case.
>
> Signed-off-by: Wenwen Wang <[email protected]>
> ---
> kernel/auditfilter.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index 63f8b3f..70a34db 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
> @@ -1128,6 +1128,8 @@ int audit_rule_change(int type, int seq, void *data, size_t datasz)
> audit_log_rule_change("remove_rule", &entry->rule, !err);
> break;
> default:
> + if (entry->rule.tree)
> + audit_put_tree(entry->rule.tree);
> err = -EINVAL;
> WARN_ON(1);
> }
Since there are only two "types" (_ADD_RULE and _DEL_RULE) and the
allocation is only three lines (audit_data_to_entry() + two lines for
error handling), maybe it makes more sense to duplicate the
audit_data_to_entry() call into the individual case statements so we
are only doing the allocations when we have a valid "type"?
--
paul moore
http://www.paul-moore.com
On Thu, Apr 18, 2019 at 4:52 PM Paul Moore <[email protected]> wrote:
>
> On Thu, Apr 18, 2019 at 1:39 PM Wenwen Wang <[email protected]> wrote:
> > In audit_rule_change(), audit_data_to_entry() is firstly invoked to
> > translate the payload data to the kernel's rule representation. In
> > audit_data_to_entry(), depending on the audit field type, an audit tree may
> > be created in audit_make_tree(), which eventually invokes kmalloc() to
> > allocate the tree. Since this tree is a temporary tree, it will be then
> > freed in the following execution, e.g., audit_add_rule() if the message
> > type is AUDIT_ADD_RULE or audit_del_rule() if the message type is
> > AUDIT_DEL_RULE. However, if the message type is neither AUDIT_ADD_RULE nor
> > AUDIT_DEL_RULE, i.e., the default case of the switch statement, this
> > temporary tree is not freed.
> >
> > To fix this issue, free the allocated tree in the default case.
> >
> > Signed-off-by: Wenwen Wang <[email protected]>
> > ---
> > kernel/auditfilter.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index 63f8b3f..70a34db 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -1128,6 +1128,8 @@ int audit_rule_change(int type, int seq, void *data, size_t datasz)
> > audit_log_rule_change("remove_rule", &entry->rule, !err);
> > break;
> > default:
> > + if (entry->rule.tree)
> > + audit_put_tree(entry->rule.tree);
> > err = -EINVAL;
> > WARN_ON(1);
> > }
>
> Since there are only two "types" (_ADD_RULE and _DEL_RULE) and the
> allocation is only three lines (audit_data_to_entry() + two lines for
> error handling), maybe it makes more sense to duplicate the
> audit_data_to_entry() call into the individual case statements so we
> are only doing the allocations when we have a valid "type"?
>
This sounds reasonable to me. I will rework the patch. Thanks!
Wenwen