superseded: [PATCH qemu-server] query-machine-capabilities: check vendor string length for strncmp

[Kaiyang Wu <wukaiyang2003@gmail.com>]

https://lore.proxmox.com/pve-devel/20260729111024.58285-2-wukaiyang@loongfans.cn/

On 2026-07-29 18:16, Fiona Ebner wrote:
> Am 29.07.26 um 10:41 AM schrieb Kaiyang Wu:
>> Gentle ping.
>>
>> Kaiyang
>>
>> On 2026-07-16 10:31, Kaiyang Wu wrote:
>>> Intel TDX and AMD SEV are both x86_64 only extensions [0] [1]. I
>>> wonder if the best approach for this issue is to just add a
>>> conditional compilation check for x86_64 target architecture.
>>>
>>> If that works I will switch to compile time architecture check in v2.
>>>
>>> [0]: https://docs.kernel.org/arch/x86/tdx.html
>>> [1]: https://docs.kernel.org/virt/kvm/x86/amd-memory-encryption.html
>>>
> 
> Yes, I think the checks for AuthenticAMD and GenuineIntel can be put
> into conditional compilation for x86_64 right now. There already is a
> conditional inside query_cpu_capabilities_sev() but that can be dropped
> afterwards.
> 
>>> On 2026-07-13 22:15, Fabian Grünbichler wrote:
>>>> On June 3, 2026 7:50 am, Kaiyang Wu wrote:
>>>>> Fix build error on unknown vendors ('fallback'):
>>>>>
>>>>>      error: ‘strncmp’ of strings of length 7 and 12 and bound of 12
>>>>> evaluates to nonzero [-Werror=string-compare]
>>>>>
>>>>> Signed-off-by: Kaiyang Wu <wukaiyang@loongfans.cn>
>>>>> ---
>>>>>    src/query-machine-capabilities/query-machine-capabilities.c | 4 ++--
>>>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/src/query-machine-capabilities/query-machine-
>>>>> capabilities.c b/src/query-machine-capabilities/query-machine-
>>>>> capabilities.c
>>>>> index abb47acd..25d06db7 100644
>>>>> --- a/src/query-machine-capabilities/query-machine-capabilities.c
>>>>> +++ b/src/query-machine-capabilities/query-machine-capabilities.c
>>>>> @@ -204,7 +204,7 @@ int main() {
>>>>>            eprintf("Error writing to file '" OUTPUT_PATH "': %s\n",
>>>>> strerror(errno));
>>>>>        }
>>>>> -    if (strncmp(vendor, "AuthenticAMD", 12) == 0) {
>>>>> +    if (strncmp(vendor, "AuthenticAMD", strnlen(vendor, 12)) == 0) {
>>>>
>>>> this is wrong - if the vendor is "Authentic" the code would now think
>>>> it's AMD.. the same would be true if vendor is "AuthenticAMDsomething",
>>>> because it would only look at the first 12 bytes (granted, that is a
>>>> pre-existing issue ;)).
>>>>
>>>> instead, we'd first need to check for the length, and if it is 12, do
>>>> the existing checks, if not, either add checks for other vendors, or
>>>> reject/abort..
>>>>
>>>>>            cpu_caps_amd_sev_t caps_sev;
>>>>>            query_cpu_capabilities_sev(&caps_sev);
>>>>> @@ -222,7 +222,7 @@ int main() {
>>>>>                caps_sev.sev_es_support ? "true" : "false",
>>>>>                caps_sev.sev_snp_support ? "true" : "false"
>>>>>            );
>>>>> -    } else if (strncmp(vendor, "GenuineIntel", 12) == 0) {
>>>>> +    } else if (strncmp(vendor, "GenuineIntel", strnlen(vendor, 12))
>>>>> == 0) {
>>>>
>>>> same applies here, but with `Genuine` (or any other substring prefix of
>>>> `GenuineIntel`)..
>>>>
>>>>>            cpu_caps_intel_tdx_t caps_tdx;
>>>>>            if (query_cpu_capabilities_tdx(&caps_tdx) == 0) {
>>>>>                ret = fprintf(file,
>>>>> -- 
>>>>> 2.52.0
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>>
>>
>>
> 
>