linux-kernel - [PATCH] evm: Fix memleak in init

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Date:   Sat,  9 Jan 2021 19:33:05 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Mimi Zohar <zohar@...ux.ibm.com>, James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...ia.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] evm: Fix memleak in init_desc

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@....edu.cn>
---
 security/integrity/evm/evm_crypto.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 168c3b78ac47..39fb31a638ac 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 +118,18 @@ 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) {
+		if (tmp_tfm)
+			crypto_free_shash(tmp_tfm);
 		return ERR_PTR(-ENOMEM);
+	}
 
 	desc->tfm = *tfm;
 
 	rc = crypto_shash_init(desc);
 	if (rc) {
+		if (tmp_tfm)
+			crypto_free_shash(tmp_tfm);
 		kfree(desc);
 		return ERR_PTR(rc);
 	}
-- 
2.17.1