On December 22, 2015 9:56:28 PM GMT+02:00, Mimi Zohar
<zo...@linux.vnet.ibm.com> wrote:
>On Tue, 2015-12-22 at 08:51 -0500, Sasha Levin wrote:
>> Commit "IMA: policy can now be updated multiple times" assumed that
>the
>> policy would be updated at least once.
>>
>> If there are zero updates, the temporary list head object will get
>added
>> to the policy list, and later dereferenced as an IMA policy object,
>which
>> means that invalid memory will be accessed.
>>
>> Signed-off-by: Sasha Levin <sasha.le...@oracle.com>
>> ---
>> security/integrity/ima/ima_policy.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/security/integrity/ima/ima_policy.c
>b/security/integrity/ima/ima_policy.c
>> index ba5d2fc..9b958b8 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -431,6 +431,9 @@ void ima_update_policy(void)
>> {
>> struct list_head *first, *last, *policy;
>>
>> + if (list_empty(&ima_temp_rules))
>> + return;
>> +
>> /* append current policy with the new rules */
>> first = (&ima_temp_rules)->next;
>> last = (&ima_temp_rules)->prev;
>
>Thanks, Sasha. By the time ima_update_policy() is called
>ima_release_policy() has already output the policy update status
>message. I guess an empty policy could be considered a valid policy.
>Could you add a msg indicating that the new policy was empty?
As far as I can say we can't get to ima_update_policy() with empty
ima_temp_rules because ima_write_policy() will set valid_policy to 0 in case of
an empty rule. I'll double check it tomorrow, but please you do that too.
cheers,
Petko
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