[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>
diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 0d4d18b..c68be24 100644
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -393,10 +393,12 @@
* u_mult_inv > 128 bytes.
*/
if (copied == 0) {
- int len;
+ unsigned int len;
spin_unlock_bh(&zcrypt_device_lock);
/* len is max 256 / 2 - 120 = 8 */
len = crt->inputdatalength / 2 - 120;
+ if (len > sizeof(z1))
+ return -EFAULT;
z1 = z2 = z3 = 0;
if (copy_from_user(&z1, crt->np_prime, len) ||
copy_from_user(&z2, crt->bp_key, len) ||
