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

[GONG Ruiqi]

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.

Fixes: 98b824ff8984 ("apparmor: refcount the pdb")
Signed-off-by: GONG Ruiqi <gongruiqi1@xxxxxxxxxx>
---
 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);
-- 
2.43.0