2016-03-21 23:00:23

by Colin King

Subject: [PATCH] selinux: fix memory leak on node_ptr on error return path

From: Colin Ian King <[email protected]>

node_ptr is not being free'd if the list allocation fails, fix
this by kfree'ing it before exiting on the error path.

Signed-off-by: Colin Ian King <[email protected]>
---
security/selinux/ss/conditional.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
index 456e1a9..5d010ef 100644
--- a/security/selinux/ss/conditional.c
+++ b/security/selinux/ss/conditional.c
@@ -332,6 +332,7 @@ static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum
list = kzalloc(sizeof(struct cond_av_list), GFP_KERNEL);
if (!list) {
rc = -ENOMEM;
+ kfree(node_ptr);
goto err;
}

--
2.7.3

2016-03-22 20:28:23

by Serge E. Hallyn

Subject: Re: [PATCH] selinux: fix memory leak on node_ptr on error return path

Quoting Colin King ([email protected]):
> From: Colin Ian King <[email protected]>
>
> node_ptr is not being free'd if the list allocation fails, fix
> this by kfree'ing it before exiting on the error path.
>
> Signed-off-by: Colin Ian King <[email protected]>

Hi,

I'm not very familiar with this code any more, but are you sure
this is needed and doesn't cause a new bug? It *looks* like
the avtab_insert_nonunique() actually inserts the node_ptr
into the policydb, and the policydb is the one that should
eventually free it.

> ---
> security/selinux/ss/conditional.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/security/selinux/ss/conditional.c b/security/selinux/ss/conditional.c
> index 456e1a9..5d010ef 100644
> --- a/security/selinux/ss/conditional.c
> +++ b/security/selinux/ss/conditional.c
> @@ -332,6 +332,7 @@ static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum
> list = kzalloc(sizeof(struct cond_av_list), GFP_KERNEL);
> if (!list) {
> rc = -ENOMEM;
> + kfree(node_ptr);
> goto err;
> }
>
> --
> 2.7.3

2016-03-22 21:35:27

by Paul Moore

Subject: Re: [PATCH] selinux: fix memory leak on node_ptr on error return path

On Tue, Mar 22, 2016 at 4:28 PM, Serge E. Hallyn <[email protected]> wrote:
> Quoting Colin King ([email protected]):
>> From: Colin Ian King <[email protected]>
>>
>> node_ptr is not being free'd if the list allocation fails, fix
>> this by kfree'ing it before exiting on the error path.
>>
>> Signed-off-by: Colin Ian King <[email protected]>
>
> Hi,
>
> I'm not very familiar with this code any more, but are you sure
> this is needed and doesn't cause a new bug? It *looks* like
> the avtab_insert_nonunique() actually inserts the node_ptr
> into the policydb, and the policydb is the one that should
> eventually free it.

Exactly. cond_insertf() calls avtab_insert_nonunique() which calls
avtab_insert_node() which adds the node to the avtab. The avtab will
get cleaned up later by the error handling code in the cond_insertf()
call chain.

--
paul moore
http://www.paul-moore.com

2016-03-22 21:38:21

by Colin King

Subject: Re: [PATCH] selinux: fix memory leak on node_ptr on error return path

On 22/03/16 21:35, Paul Moore wrote:
> On Tue, Mar 22, 2016 at 4:28 PM, Serge E. Hallyn <[email protected]> wrote:
>> Quoting Colin King ([email protected]):
>>> From: Colin Ian King <[email protected]>
>>>
>>> node_ptr is not being free'd if the list allocation fails, fix
>>> this by kfree'ing it before exiting on the error path.
>>>
>>> Signed-off-by: Colin Ian King <[email protected]>
>>
>> Hi,
>>
>> I'm not very familiar with this code any more, but are you sure
>> this is needed and doesn't cause a new bug? It *looks* like
>> the avtab_insert_nonunique() actually inserts the node_ptr
>> into the policydb, and the policydb is the one that should
>> eventually free it.
>
> Exactly. cond_insertf() calls avtab_insert_nonunique() which calls
> avtab_insert_node() which adds the node to the avtab. The avtab will
> get cleaned up later by the error handling code in the cond_insertf()
> call chain.
>
My bad, apologies.