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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>
This commit is contained in:
Heiko Carstens 2010-01-13 20:44:43 +01:00 committed by Martin Schwidefsky
parent 94e587f61e
commit 0648f5659e
1 changed files with 3 additions and 1 deletions
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4
drivers/s390/crypto/zcrypt_api.c
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@ -393,10 +393,12 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
* u_mult_inv > 128 bytes. * u_mult_inv > 128 bytes.
*/ */
if (copied == 0) { if (copied == 0) {
int len; unsigned int len;
spin_unlock_bh(&zcrypt_device_lock); spin_unlock_bh(&zcrypt_device_lock);
/* len is max 256 / 2 - 120 = 8 */ /* len is max 256 / 2 - 120 = 8 */
len = crt->inputdatalength / 2 - 120; len = crt->inputdatalength / 2 - 120;
if (len > sizeof(z1))
return -EFAULT;
z1 = z2 = z3 = 0; z1 = z2 = z3 = 0;
if (copy_from_user(&z1, crt->np_prime, len) || if (copy_from_user(&z1, crt->np_prime, len) ||
copy_from_user(&z2, crt->bp_key, len) || copy_from_user(&z2, crt->bp_key, len) ||