Code: static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
	struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
		return crypto_init_skcipher_ops_blkcipher(tfm);

	if (tfm->__crt_alg->cra_type == &crypto_ablkcipher_type ||
 	    tfm->__crt_alg->cra_type == &crypto_givcipher_type)
 		return crypto_init_skcipher_ops_ablkcipher(tfm);
 
	skcipher->setkey = alg->setkey;
 	skcipher->encrypt = alg->encrypt;
 	skcipher->decrypt = alg->decrypt;
 	skcipher->ivsize = alg->ivsize;
	skcipher->keysize = alg->max_keysize;

	if (alg->exit)
		skcipher->base.exit = crypto_skcipher_exit_tfm;

	if (alg->init)
		return alg->init(skcipher);

	return 0;
}

Vulnerability Type: DoS 
CWE ID: CWE-476
Summary: The crypto_skcipher_init_tfm function in crypto/skcipher.c in the Linux kernel through 4.11.2 relies on a setkey function that lacks a key-size check, which allows local users to cause a denial of service (NULL pointer dereference) via a crafted application.
Commit Message: crypto: skcipher - Add missing API setkey checks

The API setkey checks for key sizes and alignment went AWOL during the
skcipher conversion.  This patch restores them.

Cc: <stable@vger.kernel.org>
Fixes: 4e6c3df4d729 ("crypto: skcipher - Add low-level skcipher...")
Reported-by: Baozeng <sploving1@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>