[apparmor] [PATCH -next] apparmor: fix invalid reference on profile->disconnected

[John Johansen]

On 8/21/23 11:37, Georgia Garcia wrote:
> profile->disconnected was storing an invalid reference to the
> disconnected path. Fix it by duplicating the string using
> aa_unpack_strdup and freeing accordingly.
> 
This is going to need the Fixes tag

Fixes: 72c8a768641d ("apparmor: allow profiles to provide info to disconnected paths")

> Signed-off-by: Georgia Garcia <georgia.garcia at canonical.com>

the patch certainly addresses the issue, and I can add the Fixes tag, but unless
there is something I am missing I think we should avoid the intermediate variable
as noted below

> ---
>   security/apparmor/policy.c        | 1 +
>   security/apparmor/policy_unpack.c | 5 +++--
>   2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
> index 4817c1b30105..d7525f228c43 100644
> --- a/security/apparmor/policy.c
> +++ b/security/apparmor/policy.c
> @@ -255,6 +255,7 @@ void aa_free_profile(struct aa_profile *profile)
>   
>   	aa_put_ns(profile->ns);
>   	kfree_sensitive(profile->rename);
> +	kfree_sensitive(profile->disconnected);
>   
>   	free_attachment(&profile->attach);
>   
> diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
> index d2d740bb5618..8b2ad42c80ba 100644
> --- a/security/apparmor/policy_unpack.c
> +++ b/security/apparmor/policy_unpack.c
> @@ -804,7 +804,7 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
>   	const char *info = "failed to unpack profile";
>   	size_t ns_len;
>   	struct rhashtable_params params = { 0 };
> -	char *key = NULL;
> +	char *key = NULL, *disconnected = NULL;
>   	struct aa_data *data;
>   	int error = -EPROTO;
>   	kernel_cap_t tmpcap;
> @@ -870,7 +870,8 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
>   	}
>   
>   	/* disconnected attachment string is optional */
> -	(void) aa_unpack_str(e, &profile->disconnected, "disconnected");
> +	(void) aa_unpack_strdup(e, &disconnected, "disconnected");
> +	profile->disconnected = disconnected;

is there any reason you added the intermediate step of unpacking to &disconnected instead of just directly to the value as before?
>   
>   	/* per profile debug flags (complain, audit) */
>   	if (!aa_unpack_nameX(e, AA_STRUCT, "flags")) {