[PATCH] apparmor/lsm: Fix aa_dfa_unpack's error handling in aa_setup_dfa_engine

[Georgia Garcia]

On Thu, 2026-04-23 at 11:10 +0800, GONG Ruiqi wrote:
> aa_dfa_unpack returns ERR_PTR not NULL when it fails, but aa_put_dfa
> only checks NULL for its input, which would cause invalid memory access
> in aa_put_dfa. Set nulldfa to NULL explicitly to fix that.
> 

Thank you!

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

> Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
> Signed-off-by: GONG Ruiqi <gongruiqi1 at huawei.com>
> ---
>  security/apparmor/lsm.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
> index c1d42fc72fdb..ead2f07982b6 100644
> --- a/security/apparmor/lsm.c
> +++ b/security/apparmor/lsm.c
> @@ -2465,6 +2465,7 @@ static int __init aa_setup_dfa_engine(void)
>  			    TO_ACCEPT2_FLAG(YYTD_DATA32));
>  	if (IS_ERR(nulldfa)) {
>  		error = PTR_ERR(nulldfa);
> +		nulldfa = NULL;
>  		goto fail;
>  	}
>  	nullpdb->dfa = aa_get_dfa(nulldfa);