evm: Check also if *tfm is an error pointer in init_desc()
[ Upstream commit53de3b080d
] This patch avoids a kernel panic due to accessing an error pointer set by crypto_alloc_shash(). It occurs especially when there are many files that require an unsupported algorithm, as it would increase the likelihood of the following race condition: 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:d46eb36995
("evm: crypto hash replaced by shash") 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> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -93,7 +93,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo)
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algo = hash_algo_name[hash_algo];
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}
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if (*tfm == NULL) {
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if (IS_ERR_OR_NULL(*tfm)) {
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mutex_lock(&mutex);
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if (*tfm)
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goto out;
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