From 0648f5659e2d51659bd8f42ff30f456775c3c12d Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 13 Jan 2010 20:44:43 +0100 Subject: [PATCH] [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 Signed-off-by: Martin Schwidefsky --- drivers/s390/crypto/zcrypt_api.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c index 0d4d18bdd45c..c68be24e27d9 100644 --- a/drivers/s390/crypto/zcrypt_api.c +++ b/drivers/s390/crypto/zcrypt_api.c @@ -393,10 +393,12 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt) * 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) || -- 2.20.1