Re: [Qemu-devel] [PATCH 10/10] ui: convert VNC to use generic cipher API

[Eric Blake]

On 05/21/2015 04:56 AM, Daniel P. Berrange wrote:
> Switch the VNC server over to use the generic cipher API, this
> allows it to use the pluggable DES implementations, instead of
> being hardcoded to use QEMU's built-in impl.
> 
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
>  ui/vnc.c | 52 +++++++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 41 insertions(+), 11 deletions(-)
> 

> @@ -2515,9 +2515,11 @@ static void make_challenge(VncState *vs)
>  static int protocol_client_auth_vnc(VncState *vs, uint8_t *data, size_t len)
>  {
>      unsigned char response[VNC_AUTH_CHALLENGE_SIZE];
> -    int i, j, pwlen;
> +    size_t i, pwlen;
>      unsigned char key[8];
>      time_t now = time(NULL);
> +    QCryptoCipher *cipher;
> +    Error *err;

Leaving this uninitialized...

>  
>      if (!vs->vd->password) {
>          VNC_DEBUG("No password configured on server");
> @@ -2534,9 +2536,29 @@ static int protocol_client_auth_vnc(VncState *vs, 
> uint8_t *data, size_t len)
>      pwlen = strlen(vs->vd->password);
>      for (i=0; i<sizeof(key); i++)
>          key[i] = i<pwlen ? vs->vd->password[i] : 0;
> -    deskey(key, EN0);
> -    for (j = 0; j < VNC_AUTH_CHALLENGE_SIZE; j += 8)
> -        des(response+j, response+j);
> +
> +    cipher = qcrypto_cipher_new(
> +        QCRYPTO_CIPHER_ALG_DES_RFB,
> +        QCRYPTO_CIPHER_MODE_ECB,
> +        key, G_N_ELEMENTS(key),
> +        &err);

means that gcrypto_cipher_new may assert if it tries to set an error but
dereferences bogus memory.  Local errors must always start life at NULL.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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