ima: fix a memory leak in ima_del_digest_data_entry

hulk inclusion
category: bugfix
bugzilla: 46797
CVE: NA
Reference: https://gitee.com/openeuler/kernel/issues/I3C03N

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This patch fix a memory leak problem when deleting digest list.

hlist_del_rcu in ima_del_digest_data_entry only deletes the digest
struct from the linked list without releasing the memory it uses.
Signed-off-by: NZhang Tianxing <zhangtianxing3@huawei.com>
Reviewed-by: NRoberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

security/integrity/ima/ima_digest_list.c

@@ -120,6 +120,7 @@ static void ima_del_digest_data_entry(u8 *digest, enum hash_algo algo,
 
 	hlist_del_rcu(&d->hnext);
 	atomic_long_dec(&ima_digests_htable.len);
+	kfree(d);
 }
 
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