Re: [PATCH] audit: fix a memory leak bug

On Thu, Apr 18, 2019 at 1:39 PM Wenwen Wang <wang6495(a)umn.edu&gt; 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 <wang6495(a)umn.edu&gt; > --- > 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"?