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Re: [PATCH 4/8] registry: Fix wrong truncation of Unicode.Length
- To: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>, "win-pv-devel@xxxxxxxxxxxxxxxxxxxx" <win-pv-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Owen Smith <owen.smith@xxxxxxxxxx>
- Date: Fri, 14 Aug 2026 11:58:01 +0000
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- Delivery-date: Fri, 14 Aug 2026 11:58:09 +0000
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- Thread-index: AQHdK7681agTujSIwE+S8mNzjuInbradUQiAgAAfdVk=
- Thread-topic: [PATCH 4/8] registry: Fix wrong truncation of Unicode.Length
>On 14/08/2026 09:30, Owen Smith wrote:
>> Assisted-by: ClaudeCode:claude-opus-4.8
>> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
>> ---
>> src/common/registry.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/common/registry.c b/src/common/registry.c
>
>Other drivers will need the same patch as well.
>
>> index 1f7a73c..204e2e8 100644
>> --- a/src/common/registry.c
>> +++ b/src/common/registry.c
>> @@ -1460,11 +1460,13 @@ RegistryAnsiToSz(
>
>Should RegistryAnsiToMultiSz be updated in the same way?
>
>> if (Partial == NULL)
>> goto fail1;
>>
>> + ASSERT3U(Length * sizeof (WCHAR), <=, 0xFFFF); // MAX_USHORT
>> +
>
>If the intent is to unconditionally truncate if
>RtlAnsiStringToUnicodeString fails, I don't know if we would want
>another assert here. If that's not the case, wouldn't it be better to
>simply remove the truncation code path and fail?
>
detecting an overrun and failing would be better - I will rework this patch
>> Partial->TitleIndex = 0;
>> Partial->Type = REG_SZ;
>> Partial->DataLength = Length * sizeof (WCHAR);
>>
>> - Unicode.MaximumLength = (UCHAR)Partial->DataLength;
>> + Unicode.MaximumLength = (USHORT)Partial->DataLength;
>> Unicode.Buffer = (PWCHAR)Partial->Data;
>> Unicode.Length = 0;
>>
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