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From:   Roberto Sassu <roberto.sassu@huawei.com>
To:     <zohar@linux.ibm.com>, <syzkaller-bugs@googlegroups.com>
CC:     <linux-integrity@vger.kernel.org>,
        <linux-security-module@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <silviu.vlasceanu@huawei.com>,
        Roberto Sassu <roberto.sassu@huawei.com>
Subject: [PATCH] ima: Directly free *entry in ima_alloc_init_template() if digests is NULL
Date:   Fri, 5 Jun 2020 08:50:28 +0200
Message-ID: <20200605065028.12464-1-roberto.sassu@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

To support multiple template digests, the static array entry->digest has
been replaced with a dynamically allocated array in commit aa724fe18a8a
("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: aa724fe18a8a ("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>
---
 security/integrity/ima/ima_api.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 78e0b0a7723e..bf22de8b7ce0 100644
--- a/security/integrity/ima/ima_api.c
+++ b/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;
-- 
2.17.1