yuzu-emu/mbedtls
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Prevent bounds check bypass through overflow in PSK identity parsing

Browse source 
The check `if( *p + n > end )` in `ssl_parse_client_psk_identity` is
unsafe because `*p + n` might overflow, thus bypassing the check. As
`n` is a user-specified value up to 65K, this is relevant if the
library happens to be located in the last 65K of virtual memory.

This commit replaces the check by a safe version.
This commit is contained in:
Hanno Becker 2017-06-26 13:52:14 +01:00
parent 5a1c0e7162
commit 83c9f495ff
1 changed files with 2 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
library/ssl_srv.c
View file

@ -3436,7 +3436,7 @@ static int ssl_parse_client_psk_identity( mbedtls_ssl_context *ssl, unsigned cha
/*
* Receive client pre-shared key identity name
*/
if( *p + 2 > end )
if( end - *p < 2 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
@ -3445,7 +3445,7 @@ static int ssl_parse_client_psk_identity( mbedtls_ssl_context *ssl, unsigned cha
n = ( (*p)[0] << 8 ) | (*p)[1];
*p += 2;
if( n < 1 || n > 65535 || *p + n > end )
if( n < 1 || n > 65535 || n > (size_t) ( end - *p ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );