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More forceful clearing of stack memory with keys

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gcc 8.3.0 was apparently clever enough to optimize away the previously
used os_memset() to explicitly clear a stack buffer that contains keys
when that clearing happened just before returning from the function.
Since memset_s() is not exactly portable (or commonly available yet..),
use a less robust mechanism that is still pretty likely to prevent
current compilers from optimizing the explicit clearing of the memory
away.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2019-05-26 00:47:17 +03:00
parent e1923f5b6a
commit 31bc66e4d1
25 changed files with 98 additions and 72 deletions
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6
src/eap_peer/eap_peap.c
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@ -295,7 +295,7 @@ static int eap_peap_derive_cmk(struct eap_sm *sm, struct eap_peap_data *data)
res = peap_prfplus(data->peap_version, tk, 40,
"Inner Methods Compound Keys",
isk, sizeof(isk), imck, sizeof(imck));
os_memset(isk, 0, sizeof(isk));
forced_memzero(isk, sizeof(isk));
if (res < 0)
return -1;
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IMCK (IPMKj)",
@ -305,7 +305,7 @@ static int eap_peap_derive_cmk(struct eap_sm *sm, struct eap_peap_data *data)
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IPMK (S-IPMKj)", data->ipmk, 40);
os_memcpy(data->cmk, imck + 40, 20);
wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: CMK (CMKj)", data->cmk, 20);
os_memset(imck, 0, sizeof(imck));
forced_memzero(imck, sizeof(imck));
return 0;
}
@ -1267,7 +1267,7 @@ static u8 * eap_peap_getKey(struct eap_sm *sm, void *priv, size_t *len)
os_memcpy(key, csk, EAP_TLS_KEY_LEN);
wpa_hexdump(MSG_DEBUG, "EAP-PEAP: Derived key",
key, EAP_TLS_KEY_LEN);
os_memset(csk, 0, sizeof(csk));
forced_memzero(csk, sizeof(csk));
} else
os_memcpy(key, data->key_data, EAP_TLS_KEY_LEN);