Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull apparmor bugfix from James Morris.
Fix a possibly unbounded recursion by iterating over the entries instead.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
apparmor: fix IRQ stack overflow during free_profile
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index cf5fd22..8132003 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -724,6 +724,8 @@
*/
static void free_profile(struct aa_profile *profile)
{
+ struct aa_profile *p;
+
AA_DEBUG("%s(%p)\n", __func__, profile);
if (!profile)
@@ -751,7 +753,27 @@
aa_put_dfa(profile->xmatch);
aa_put_dfa(profile->policy.dfa);
- aa_put_profile(profile->replacedby);
+ /* put the profile reference for replacedby, but not via
+ * put_profile(kref_put).
+ * replacedby can form a long chain that can result in cascading
+ * frees that blows the stack because kref_put makes a nested fn
+ * call (it looks like recursion, with free_profile calling
+ * free_profile) for each profile in the chain lp#1056078.
+ */
+ for (p = profile->replacedby; p; ) {
+ if (atomic_dec_and_test(&p->base.count.refcount)) {
+ /* no more refs on p, grab its replacedby */
+ struct aa_profile *next = p->replacedby;
+ /* break the chain */
+ p->replacedby = NULL;
+ /* now free p, chain is broken */
+ free_profile(p);
+
+ /* follow up with next profile in the chain */
+ p = next;
+ } else
+ break;
+ }
kzfree(profile);
}
