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    SubjectRe: [PATCH] IMA: policy can be updated zero times
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    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.levin@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?

    Mimi



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