From: Roberto Sassu <roberto.sassu@huawei.com>
To: <zohar@linux.ibm.com>
Cc: <linux-integrity@vger.kernel.org>,
<linux-security-module@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
<krzysztof.struczynski@huawei.com>, <silviu.vlasceanu@huawei.com>,
"Roberto Sassu" <roberto.sassu@huawei.com>,
<stable@vger.kernel.org>
Subject: [PATCH 2/5] evm: Check also if *tfm is an error pointer in init_desc()
Date: Wed, 25 Mar 2020 17:11:13 +0100 [thread overview]
Message-ID: <20200325161116.7082-2-roberto.sassu@huawei.com> (raw)
In-Reply-To: <20200325161116.7082-1-roberto.sassu@huawei.com>
The mutex in init_desc(), introduced by commit 97426f985729 ("evm: prevent
racing during tfm allocation") prevents two tasks to concurrently set *tfm.
However, checking if *tfm is NULL is not enough, as crypto_alloc_shash()
can return an error pointer. The following sequence can happen:
Task A: *tfm = crypto_alloc_shash() <= error pointer
Task B: if (*tfm == NULL) <= *tfm is not NULL, use it
Task B: rc = crypto_shash_init(desc) <= panic
Task A: *tfm = NULL
This patch uses the IS_ERR_OR_NULL macro to determine whether or not a new
crypto context must be created.
Cc: stable@vger.kernel.org
Fixes: 97426f985729 ("evm: prevent racing during tfm allocation")
Co-developed-by: Krzysztof Struczynski <krzysztof.struczynski@huawei.com>
Signed-off-by: Krzysztof Struczynski <krzysztof.struczynski@huawei.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/evm/evm_crypto.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index 35682852ddea..77ad1e5a93e4 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -91,7 +91,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
algo = hash_algo_name[hash_algo];
}
- if (*tfm == NULL) {
+ if (IS_ERR_OR_NULL(*tfm)) {
mutex_lock(&mutex);
if (*tfm)
goto out;
--
2.17.1
next prev parent reply other threads:[~2020-03-25 16:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 16:11 [PATCH 1/5] ima: Set file->f_mode instead of file->f_flags in ima_calc_file_hash() Roberto Sassu
2020-03-25 16:11 ` Roberto Sassu [this message]
2020-04-22 13:45 ` [PATCH 2/5] evm: Check also if *tfm is an error pointer in init_desc() Mimi Zohar
2020-04-22 15:37 ` Roberto Sassu
2020-03-25 16:11 ` [PATCH 3/5] ima: Fix ima digest hash table key calculation Roberto Sassu
2020-04-22 20:56 ` Mimi Zohar
2020-04-23 10:21 ` Roberto Sassu
2020-04-23 16:53 ` Mimi Zohar
2020-04-24 12:18 ` Roberto Sassu
2020-04-24 14:45 ` Mimi Zohar
2020-03-25 16:14 ` [PATCH 4/5] ima: Remove redundant policy rule set in add_rules() Roberto Sassu
2020-03-25 16:14 ` [PATCH 5/5] ima: Remove unused build_ima_appraise variable Roberto Sassu
2020-04-22 22:59 ` Mimi Zohar
2020-04-22 12:03 ` [PATCH 1/5] ima: Set file->f_mode instead of file->f_flags in ima_calc_file_hash() Mimi Zohar
2020-04-22 15:39 ` Roberto Sassu
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