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    SubjectRe: [PATCH 2/4] Drivers: hv: Support the newly introduced KVP messages in the driver
    On Mon, Mar 12, 2012 at 12:36:53PM +0000, KY Srinivasan wrote:
    > Dan,
    > I am sorry for not being as precise as I should be:
    > utf16s_to_utf8s() takes two length parameters - the length of the utf16 string
    > that is to be converted and the second the length of the utf8 output string.
    > The windows host manipulates all string in utf16 encoding and the string we get
    > from the host is guaranteed to be less than or equal to MAX value that we have
    > including the terminating character. In my code, I simply pass the length of the
    > utf16 string as received from the host.
    >
    > The parameter that I am currently passing MAX length value is the "maxout"
    > parameter of the utf16s_utf8s() function. This by definition is the size of the
    > output buffer and in this case it happens to be MAX characters big.
    >

    I also think I'm not being as clear as I should... I understand
    that you trust the input; I'm say that for correctness sake you
    should specify a output size which leaves room for the NUL char.

    I can't say I know this code very well so I could be wrong, but it's
    what we do inside usb_string() for example. Can someone who knows
    the code check if we should do something like this:

    diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
    index 3b2eeaa..3a97f52 100644
    --- a/drivers/hv/hv_kvp.c
    +++ b/drivers/hv/hv_kvp.c
    @@ -173,7 +173,7 @@ kvp_send_key(struct work_struct *dummy)
    in_msg->body.kvp_set.data.value_size,
    UTF16_LITTLE_ENDIAN,
    message->body.kvp_set.data.value,
    - HV_KVP_EXCHANGE_MAX_VALUE_SIZE) + 1;
    + HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
    break;

    case REG_U32:
    @@ -208,7 +208,7 @@ kvp_send_key(struct work_struct *dummy)
    in_msg->body.kvp_set.data.key_size,
    UTF16_LITTLE_ENDIAN,
    message->body.kvp_set.data.key,
    - HV_KVP_EXCHANGE_MAX_KEY_SIZE) + 1;
    + HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;

    break;

    @@ -219,7 +219,7 @@ kvp_send_key(struct work_struct *dummy)
    in_msg->body.kvp_delete.key_size,
    UTF16_LITTLE_ENDIAN,
    message->body.kvp_delete.key,
    - HV_KVP_EXCHANGE_MAX_KEY_SIZE) + 1;
    + HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;

    break;
    [unhandled content-type:application/pgp-signature]
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