Looks like issue in handling active_nodes count in 4.19 kernel .

[Stephen Smalley]

On 12/19/19 4:48 AM, Ravi Kumar Siddojigari wrote:
> Sorry , Re-adding the patch  below as requested.
> 
> Stephen ,
> Issue is fixed with this  2 changes , Issue as even reproduced on v4.14 and  similar changes work there also .

It would be preferable if you sent the patch directly via git send-email 
or similar.  In any event, for the final version, we should drop the 
Change-Id because it is Android-specific and we should add a Fixes line 
like so:

Fixes: fa1aa143ac4a ("selinux: extended permissions for ioctls")

Given the behavior you are describing and the fact that you could 
reproduce it on v4.14 as well, I would recommend marking both it and 
Paul's earlier patch for stable (Paul will do this if he agrees; no 
action required by you).

> 
> --
>  From 77c618006397c7a65ead257f3cb4e4fe3da2d4b8 Mon Sep 17 00:00:00 2001
> From: Jaihind Yadav <jaihindyadav at codeaurora.org>
> Date: Tue, 17 Dec 2019 17:25:47 +0530
> Subject: [PATCH] selinux: ensure we cleanup the internal AVC counters on error
>   in avc_update()
> 
> In AVC update we don't call avc_node_kill() when avc_xperms_populate()
> fails, resulting in the avc->avc_cache.active_nodes counter having a
> false value. In last patch this changes was missed , so correcting it.
> 
> Change-Id: Ic0298162cc766c0f21be7ab232e259766654dad3
> Signed-off-by: Ravi Kumar Siddojigari <rsiddoji at codeaurora.org>
> ---
>   security/selinux/avc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> index 91d24c2..3d1cff2 100644
> --- a/security/selinux/avc.c
> +++ b/security/selinux/avc.c
> @@ -913,7 +913,7 @@ static int avc_update_node(struct selinux_avc *avc,
>          if (orig->ae.xp_node) {
>                  rc = avc_xperms_populate(node, orig->ae.xp_node);
>                  if (rc) {
> -                       kmem_cache_free(avc_node_cachep, node);
> +                       avc_node_kill(avc, node);
>                          goto out_unlock;
>                  }
>          }
> --
> 1.9.1
> 
> Br,
>