From: Roberto Sassu Date: Mon, 27 Apr 2020 10:28:56 +0000 (+0200) Subject: evm: Check also if *tfm is an error pointer in init_desc() X-Git-Tag: v5.15~3864^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=53de3b080d5eae31d0de219617155dcc34e7d698;p=platform%2Fkernel%2Flinux-starfive.git evm: Check also if *tfm is an error pointer in init_desc() 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: d46eb3699502b ("evm: crypto hash replaced by shash") Co-developed-by: Krzysztof Struczynski Signed-off-by: Krzysztof Struczynski Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 3568285..77ad1e5 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;