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OpenSSL: Handle EVP_PKEY_derive() secret_len changes for ECDH

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It looks like EVP_PKEY_derive() may change the returned length of the
buffer from the initial length determination (NULL buffer) to the
fetching of the value. Handle this by updating the secret length based
on the second call instead of the first one. This fixes some cases where
ECDH result has been used with extra data (zeros in the end) with OWE or
FILS PFS.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2019-08-04 15:03:08 +03:00
parent 29ef1c5ee4
commit d001fe31ab
1 changed files with 6 additions and 2 deletions
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8
src/crypto/crypto_openssl.c
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@ -2059,13 +2059,17 @@ struct wpabuf * crypto_ecdh_set_peerkey(struct crypto_ecdh *ecdh, int inc_y,
secret = wpabuf_alloc(secret_len);
if (!secret)
goto fail;
if (EVP_PKEY_derive(ctx, wpabuf_put(secret, secret_len),
&secret_len) != 1) {
if (EVP_PKEY_derive(ctx, wpabuf_put(secret, 0), &secret_len) != 1) {
wpa_printf(MSG_ERROR,
"OpenSSL: EVP_PKEY_derive(2) failed: %s",
ERR_error_string(ERR_get_error(), NULL));
goto fail;
}
if (secret->size != secret_len)
wpa_printf(MSG_DEBUG,
"OpenSSL: EVP_PKEY_derive(2) changed secret_len %d -> %d",
(int) secret->size, (int) secret_len);
wpabuf_put(secret, secret_len);
done:
BN_free(x);