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SubjectRe: [PATCH AUTOSEL 5.5 190/542] selinux: ensure we cleanup the internal AVC counters on error in avc_insert()
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On 2/14/20 10:43 AM, Sasha Levin wrote:
> 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>

You should also apply 030b995ad9ece9fa2d218af4429c1c78c2342096
("selinux: ensure we cleanup the internal AVC counters on error in
avc_update()") which fixes one additional instance of the same kind of
bug not addressed by this patch.

> ---
> 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;
> }
>
>

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