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Merge branch 'development-restricted' into prepare-rc-2.22.0-updated

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* development-restricted:
  Parse HelloVerifyRequest buffer overread: add changelog entry
  Parse HelloVerifyRequest: avoid buffer overread at the start
  Parse HelloVerifyRequest: avoid buffer overread on the cookie
This commit is contained in:
Manuel Pégourié-Gonnard 2020-04-09 12:17:11 +02:00
commit 28482397d3
2 changed files with 16 additions and 2 deletions
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2
ChangeLog
View file

@ -18,6 +18,8 @@ Security
untrusted operating system attacking a secure enclave) to fully recover
an ECDSA private key. Found and reported by Alejandro Cabrera Aldaya,
Billy Brumley and Cesar Pereida Garcia. CVE-2020-10932
* Fix a potentially remotely exploitable buffer overread in a
DTLS client when parsing the Hello Verify Request message.
Features
* The new build option MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH automatically

16
library/ssl_cli.c
View file

@ -1578,6 +1578,19 @@ static int ssl_parse_hello_verify_request( mbedtls_ssl_context *ssl )
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse hello verify request" ) );
/* Check that there is enough room for:
* - 2 bytes of version
* - 1 byte of cookie_len
*/
if( mbedtls_ssl_hs_hdr_len( ssl ) + 3 > ssl->in_msglen )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "incoming HelloVerifyRequest message is too short" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
}
/*
* struct {
* ProtocolVersion server_version;
@ -1606,8 +1619,6 @@ static int ssl_parse_hello_verify_request( mbedtls_ssl_context *ssl )
}
cookie_len = *p++;
MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
if( ( ssl->in_msg + ssl->in_msglen ) - p < cookie_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
@ -1616,6 +1627,7 @@ static int ssl_parse_hello_verify_request( mbedtls_ssl_context *ssl )
MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
mbedtls_free( ssl->handshake->verify_cookie );