[PATCH] [v2] evm: Fix memleak in init_desc

From: Dinghao Liu <dinghao.liu@zju.edu.cn>
To: dinghao.liu@zju.edu.cn, kjlu@umn.edu
Cc: Mimi Zohar <zohar@linux.ibm.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Dmitry Kasatkin <dmitry.kasatkin@nokia.com>,
	linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] [v2] evm: Fix memleak in init_desc
Date: Sun, 10 Jan 2021 16:02:53 +0800	[thread overview]
Message-ID: <20210110080253.32345-1-dinghao.liu@zju.edu.cn> (raw)

When kmalloc() fails, tmp_tfm allocated by
crypto_alloc_shash() has not been freed, which
leads to memleak.

Fixes: d46eb3699502b ("evm: crypto hash replaced by shash")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
---

Changelog:

v2: - Remove checks against tmp_tfm before freeing.
---
 security/integrity/evm/evm_crypto.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 168c3b78ac47..a6dd47eb086d 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -73,7 +73,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
 {
 	long rc;
 	const char *algo;
-	struct crypto_shash **tfm, *tmp_tfm;
+	struct crypto_shash **tfm, *tmp_tfm = NULL;
 	struct shash_desc *desc;
 
 	if (type == EVM_XATTR_HMAC) {
@@ -118,13 +118,16 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
 alloc:
 	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
 			GFP_KERNEL);
-	if (!desc)
+	if (!desc) {
+		crypto_free_shash(tmp_tfm);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	desc->tfm = *tfm;
 
 	rc = crypto_shash_init(desc);
 	if (rc) {
+		crypto_free_shash(tmp_tfm);
 		kfree(desc);
 		return ERR_PTR(rc);
 	}
-- 
2.17.1

