From: Roberto Sassu <[email protected]> [ Upstream commit 53de3b080d5eae31d0de219617155dcc34e7d698 ]
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: [email protected] Fixes: d46eb3699502b ("evm: crypto hash replaced by shash") Co-developed-by: Krzysztof Struczynski <[email protected]> Signed-off-by: Krzysztof Struczynski <[email protected]> Signed-off-by: Roberto Sassu <[email protected]> Signed-off-by: Mimi Zohar <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- 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 c783fefa558a..e034dc21421e 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -90,7 +90,7 @@ static struct shash_desc *init_desc(char type) algo = evm_hash; } - if (*tfm == NULL) { + if (IS_ERR_OR_NULL(*tfm)) { mutex_lock(&mutex); if (*tfm) goto out; -- 2.25.1
