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[S390] zcrypt: add sanity check before copy_from_user()
It's not obvious that copy_from_user() is called with a sane length parameter here. Even though it currently seems to be correct better add a check to prevent stack corruption / exploits. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -393,10 +393,12 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
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* u_mult_inv > 128 bytes.
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*/
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if (copied == 0) {
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int len;
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unsigned int len;
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spin_unlock_bh(&zcrypt_device_lock);
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/* len is max 256 / 2 - 120 = 8 */
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len = crt->inputdatalength / 2 - 120;
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if (len > sizeof(z1))
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return -EFAULT;
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z1 = z2 = z3 = 0;
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if (copy_from_user(&z1, crt->np_prime, len) ||
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copy_from_user(&z2, crt->bp_key, len) ||
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