ima: Directly free *entry in ima_alloc_init_template() if digests is NULL

To support multiple template digests, the static array entry->digest has
been replaced with a dynamically allocated array in commit aa724fe1
("ima: Switch to dynamically allocated buffer for template digests"). The
array is allocated in ima_alloc_init_template() and if the returned pointer
is NULL, ima_free_template_entry() is called.

However, (*entry)->template_desc is not yet initialized while it is used by
ima_free_template_entry(). This patch fixes the issue by directly freeing
*entry without calling ima_free_template_entry().

Fixes: aa724fe1 ("ima: Switch to dynamically allocated buffer for template digests")
Reported-by: syzbot+223310b454ba6b75974e@syzkaller.appspotmail.com
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity/ima/ima_api.c

@@ -55,8 +55,9 @@ int ima_alloc_init_template(struct ima_event_data *event_data,
 	digests = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots,
 			  sizeof(*digests), GFP_NOFS);
 	if (!digests) {
-		result = -ENOMEM;
-		goto out;
+		kfree(*entry);
+		*entry = NULL;
+		return -ENOMEM;
 	}
 
 	(*entry)->digests = digests;