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pkwrite: fix buffer overrun

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This commit fixes potential buffer overrun in:
- pk_write_rsa_der
- pk_write_ec_pubkey

In both functions, when dealing with opaque keys, there was no
check that the provided buffer was large enough to contain the
key being exported. This commit fixes this problem and it also
adds some testing in test_suite_pkwrite to trigger these checks.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti
2024-10-11 14:55:24 +02:00
committed by Gilles Peskine
parent 71c569d44b
commit 5f1c8a720f
2 changed files with 29 additions and 4 deletions
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14
library/pkwrite.c
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@ -65,17 +65,21 @@ static int pk_write_rsa_der(unsigned char **p, unsigned char *buf,
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if (mbedtls_pk_get_type(pk) == MBEDTLS_PK_OPAQUE) {
uint8_t tmp[PSA_EXPORT_KEY_PAIR_MAX_SIZE];
size_t len = 0, tmp_len = 0;
size_t tmp_len = 0;
if (psa_export_key(pk->priv_id, tmp, sizeof(tmp), &tmp_len) != PSA_SUCCESS) {
return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
}
/* Ensure there's enough space in the provided buffer before copying data into it. */
if (tmp_len > (size_t) (*p - buf)) {
mbedtls_platform_zeroize(tmp, sizeof(tmp));
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
*p -= tmp_len;
memcpy(*p, tmp, tmp_len);
len += tmp_len;
mbedtls_platform_zeroize(tmp, sizeof(tmp));
return (int) len;
return (int) tmp_len;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
return mbedtls_rsa_write_key(mbedtls_pk_rsa(*pk), buf, p);
@ -125,6 +129,10 @@ static int pk_write_ec_pubkey(unsigned char **p, unsigned char *start,
if (psa_export_public_key(pk->priv_id, buf, sizeof(buf), &len) != PSA_SUCCESS) {
return MBEDTLS_ERR_PK_BAD_INPUT_DATA;
}
/* Ensure there's enough space in the provided buffer before copying data into it. */
if (len > (size_t) (*p - start)) {
return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
}
*p -= len;
memcpy(*p, buf, len);
return (int) len;