linux-hardening - Re: [PATCH][next] hyperv: Avoid -Wflex-array-member-not-at-end warning

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Message-ID: <cb7d056c-1647-409a-a6ca-0be264137041@embeddedor.com>
Date: Fri, 19 Dec 2025 11:53:16 +0900
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Wei Liu <wei.liu@...nel.org>, "Gustavo A. R. Silva"
 <gustavoars@...nel.org>
Cc: "K. Y. Srinivasan" <kys@...rosoft.com>,
 Haiyang Zhang <haiyangz@...rosoft.com>, Dexuan Cui <decui@...rosoft.com>,
 Long Li <longli@...rosoft.com>, linux-hyperv@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH][next] hyperv: Avoid -Wflex-array-member-not-at-end
 warning

On 12/19/25 04:42, Wei Liu wrote:
> On Fri, Dec 12, 2025 at 03:44:50PM +0900, Gustavo A. R. Silva wrote:
>> -Wflex-array-member-not-at-end was introduced in GCC-14, and we are
>> getting ready to enable it, globally.
>>
>> Use the new __TRAILING_OVERLAP() helper to fix the following warning:
>>
>> include/hyperv/hvgdk_mini.h:581:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
>>
>> This helper creates a union between a flexible-array member (FAM) and a
>> set of MEMBERS that would otherwise follow it.
>>
>> This overlays the trailing MEMBER u64 gva_list[]; onto the FAM
>> struct hv_tlb_flush_ex::hv_vp_set.bank_contents[], while keeping
>> the FAM and the start of MEMBER aligned.
>>
>> The static_assert() ensures this alignment remains, and it's
>> intentionally placed inmediately after the related structure --no
>> blank line in between.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> 
> Applied. I fixed a typo in the commit message ("inmediately" ->
> "immediately").

Awesome. :)

Thanks
-Gustavo