[PATCH 5.5 123/399] selinux: ensure we cleanup the internal AVC counters on error in avc_insert()

Greg Kroah-Hartman
2020-02-21T07:48:55Z

From: Paul Moore <paul@paul-moore.com>

[ Upstream commit d8db60cb23e49a92cf8cada3297395c7fa50fdf8 ]

Fix avc_insert() to call avc_node_kill() if we've already allocated
an AVC node and the code fails to insert the node in the cache.

Fixes: fa1aa143ac4a ("selinux: extended permissions for ioctls")
Reported-by: rsiddoji@codeaurora.org
Suggested-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/selinux/avc.c | 51 ++++++++++++++++++++----------------------
1 file changed, 24 insertions(+), 27 deletions(-)

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index 23dc888ae3056..6646300f7ccb2 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -617,40 +617,37 @@ static struct avc_node *avc_insert(struct selinux_avc *avc,
struct avc_node *pos, *node = NULL;
int hvalue;
unsigned long flag;
+ spinlock_t *lock;
+ struct hlist_head *head;

if (avc_latest_notif_update(avc, avd->seqno, 1))
- goto out;
+ return NULL;

node = avc_alloc_node(avc);
- if (node) {
- struct hlist_head *head;
- spinlock_t *lock;
- int rc = 0;
-
- hvalue = avc_hash(ssid, tsid, tclass);
- avc_node_populate(node, ssid, tsid, tclass, avd);
- rc = avc_xperms_populate(node, xp_node);
- if (rc) {
- kmem_cache_free(avc_node_cachep, node);
- return NULL;
- }
- head = &avc->avc_cache.slots[hvalue];
- lock = &avc->avc_cache.slots_lock[hvalue];
+ if (!node)
+ return NULL;

- spin_lock_irqsave(lock, flag);
- hlist_for_each_entry(pos, head, list) {
- if (pos->ae.ssid == ssid &&
- pos->ae.tsid == tsid &&
- pos->ae.tclass == tclass) {
- avc_node_replace(avc, node, pos);
- goto found;
- }
+ avc_node_populate(node, ssid, tsid, tclass, avd);
+ if (avc_xperms_populate(node, xp_node)) {
+ avc_node_kill(avc, node);
+ return NULL;
+ }
+
+ hvalue = avc_hash(ssid, tsid, tclass);
+ head = &avc->avc_cache.slots[hvalue];
+ lock = &avc->avc_cache.slots_lock[hvalue];
+ spin_lock_irqsave(lock, flag);
+ hlist_for_each_entry(pos, head, list) {
+ if (pos->ae.ssid == ssid &&
+ pos->ae.tsid == tsid &&
+ pos->ae.tclass == tclass) {
+ avc_node_replace(avc, node, pos);
+ goto found;
}
- hlist_add_head_rcu(&node->list, head);
-found:
- spin_unlock_irqrestore(lock, flag);
}
-out:
+ hlist_add_head_rcu(&node->list, head);
+found:
+ spin_unlock_irqrestore(lock, flag);
return node;
}

--
2.20.1