From 76b3138192e6ffec334269b1426fd0d100ba962b Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Tue, 12 Sep 2017 07:04:26 +0200 Subject: [PATCH] s390/zcrypt: Explicitly check input data length. The function to prepare MEX type 50 ap messages did not explicitly check for the data length in case of data > 512 bytes. Instead the function assumes the boundary check done in the ioctl function will always reject requests with invalid data length values. However, screening just the function code may give the illusion, that there may be a gap which could be exploited by userspace for buffer overwrite attacks. Signed-off-by: Harald Freudenberger Signed-off-by: Martin Schwidefsky --- drivers/s390/crypto/zcrypt_msgtype50.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/s390/crypto/zcrypt_msgtype50.c b/drivers/s390/crypto/zcrypt_msgtype50.c index 6dd5d7c58dd0..db5bde47dfb0 100644 --- a/drivers/s390/crypto/zcrypt_msgtype50.c +++ b/drivers/s390/crypto/zcrypt_msgtype50.c @@ -240,8 +240,7 @@ static int ICAMEX_msg_to_type50MEX_msg(struct zcrypt_queue *zq, mod = meb2->modulus + sizeof(meb2->modulus) - mod_len; exp = meb2->exponent + sizeof(meb2->exponent) - mod_len; inp = meb2->message + sizeof(meb2->message) - mod_len; - } else { - /* mod_len > 256 = 4096 bit RSA Key */ + } else if (mod_len <= 512) { struct type50_meb3_msg *meb3 = ap_msg->message; memset(meb3, 0, sizeof(*meb3)); ap_msg->length = sizeof(*meb3); @@ -251,7 +250,8 @@ static int ICAMEX_msg_to_type50MEX_msg(struct zcrypt_queue *zq, mod = meb3->modulus + sizeof(meb3->modulus) - mod_len; exp = meb3->exponent + sizeof(meb3->exponent) - mod_len; inp = meb3->message + sizeof(meb3->message) - mod_len; - } + } else + return -EINVAL; if (copy_from_user(mod, mex->n_modulus, mod_len) || copy_from_user(exp, mex->b_key, mod_len) ||