From de7c4cc947f9f56f61520ee7edaf380434a98c8d Mon Sep 17 00:00:00 2001 From: John Johansen Date: Wed, 16 Dec 2015 18:09:10 -0800 Subject: [PATCH] apparmor: fix refcount race when finding a child profile When finding a child profile via an rcu critical section, the profile may be put and scheduled for deletion after the child is found but before its refcount is incremented. Protect against this by repeating the lookup if the profiles refcount is 0 and is one its way to deletion. Signed-off-by: John Johansen Acked-by: Seth Arnold --- security/apparmor/policy.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index ca402d028db8..780712553651 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -766,7 +766,9 @@ struct aa_profile *aa_find_child(struct aa_profile *parent, const char *name) struct aa_profile *profile; rcu_read_lock(); - profile = aa_get_profile(__find_child(&parent->base.profiles, name)); + do { + profile = __find_child(&parent->base.profiles, name); + } while (profile && !aa_get_profile_not0(profile)); rcu_read_unlock(); /* refcount released by caller */