From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lamorak.hansenpartnership.com (lamorak.hansenpartnership.com [198.37.111.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C35F913C914; Tue, 7 Oct 2025 22:56:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.37.111.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759877781; cv=none; b=WCEosTkioyvbiwZpZevhk3rCWeiJ25o0Phw54rG28ixe1o6whOXMydgF1f6kMbGRGG2wA+8vWpbeQZS5LcAAKruH1ufun58n3hudqyucxfAVBam8wjb8uH4rCrTSqYWYPqHrAaH3epjXeSMjIB5fH2PaB+mjNRzZ+Pci/GHV7t0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759877781; c=relaxed/simple; bh=i2dDAMsTI7fT6cwWSdhsTu+pxbEbqJI6wucU4z41XAw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=gQNelI6fs/oR+om7oVPr0JKMs1tI0AZdormLgJISxko79xjyNguo2uAbxBUr9wI1ib/E77HUWQiUbOCO6UepzTtkB13Lvr0jlnw2Z7XRtqqrPm4OlKDry4uzwOhW5wEP8mfMMftiajj7OXXRgkzPUzG7ZtOY3utiGauiyh72JM0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=XLJdUC2V; arc=none smtp.client-ip=198.37.111.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="XLJdUC2V" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1759877777; bh=i2dDAMsTI7fT6cwWSdhsTu+pxbEbqJI6wucU4z41XAw=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=XLJdUC2Vt7vZePxqghPJsHvhG1Szz89GE1M0WJcd8RoRWTCY71t9m4RUFhKcZoLG/ 0L2D9ZDIvr5q1J9pYG8zyyK10jbUq7ddOY/REBG2gPGBT10CZHVdq60D6UOx9pvJ4R eOshiAf4wfyZa7a3I541kvLQqiRHxmiCByQTdcW8= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::a774]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lamorak.hansenpartnership.com (Postfix) with ESMTPSA id 3CE0B1C0179; Tue, 07 Oct 2025 18:56:17 -0400 (EDT) Message-ID: Subject: Re: [PATCH v2][next] scsi: megaraid_sas: Avoid a couple -Wflex-array-member-not-at-end warnings From: James Bottomley To: "Gustavo A. R. Silva" , "Gustavo A. R. Silva" , Kashyap Desai , Sumit Saxena , Shivasharan S , Chandrakanth patil , "Martin K. Petersen" Cc: megaraidlinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Date: Tue, 07 Oct 2025 18:56:16 -0400 In-Reply-To: <5b23ae5a-bd47-49c7-bca7-7019abc631f7@embeddedor.com> References: <3a80fd1d-5a05-4db3-9dda-3ad38bedfb38@embeddedor.com> <4cf727c56c4fda8d28df920214b3824c9739bc8f.camel@HansenPartnership.com> <5b23ae5a-bd47-49c7-bca7-7019abc631f7@embeddedor.com> Autocrypt: addr=James.Bottomley@HansenPartnership.com; prefer-encrypt=mutual; keydata=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 8mT2Eh9SkH+YVOmaKsajgZgrBxA7fWmGoxXswEVxJIFj3vW7yNc0C5HaUdYa5iGOMs4kg2ht4s7yy7NRQuh7BifWjo6BQ6k4S1H+6axZucxhSV1L6zN9d+lr3Xo/vy1unzA== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-10-07 at 15:18 +0100, Gustavo A. R. Silva wrote: >=20 >=20 > On 10/7/25 12:59, James Bottomley wrote: > > On Tue, 2025-10-07 at 11:43 +0100, Gustavo A. R. Silva wrote: > > > Hi all, > > >=20 > > > Friendly ping: who can take this, please? > >=20 > > After what happened with the qla2xxx driver, everyone is a bit wary > > of these changes, particularly when they affect structures shared > > with the hardware. Megaraid is a broadcom acquisition so although > > maintained it might take them a while to check this. >=20 > I've been in constant communication with the people involved. So far, > none of them has expressed any concerns about this to me. However, I > appreciate your feedback. >=20 > In any case, I promptly submitted a bugfix minutes after getting the > report. I'm not criticizing the response, just saying that problems like this cause me to think that someone who understands and can test the hardware needs to look at this. However ... > > However, you could help us with this: as I understand it (there is > > a bit of a no documentation problem here), the TRAILING_OVERLAP > > formalism merely gets the compiler not to warn about the situation > > rather than actually changing anything in the layout of the > > structure?=C2=A0 In which case you should be able to demonstrate the > > binary produced before and after this patch is the same, which > > would very much reduce the risk of taking it. >=20 > This is quite simple. Here you go the pahole output before and after > changes. >=20 > BEFORE CHANGES: >=20 > pahole -C MR_FW_RAID_MAP_ALL drivers/scsi/megaraid/megaraid_sas_fp.o > struct MR_FW_RAID_MAP_ALL { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct MR_FW_RAID_MAP=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 raidMap;=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /*=C2=A0=C2=A0=C2=A0=C2=A0 0 > 10408 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* --- cacheline 162 bou= ndary (10368 bytes) was 40 bytes ago > --- */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct MR_LD_SPAN_MAP=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 ldSpanMap[64];=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0 /* 10408 > 161792 */ >=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* size: 172200, cacheli= nes: 2691, members: 2 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* last cacheline: 40 by= tes */ > }; >=20 > AFTER CHANGES: >=20 > pahole -C MR_FW_RAID_MAP_ALL drivers/scsi/megaraid/megaraid_sas_fp.o > struct MR_FW_RAID_MAP_ALL { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 union { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 struct MR_FW_RAID_MAP raidMap;=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /*=C2=A0=C2=A0=C2=A0=C2=A0 0 > 10408 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 struct { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 un= signed char __offset_to_FAM[10408]; /*=C2=A0=C2=A0=C2=A0=C2=A0 > 0 10408 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /*= --- cacheline 162 boundary (10368 bytes) > was 40 bytes ago --- */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 st= ruct MR_LD_SPAN_MAP ldSpanMap[64]; /* > 10408 161792 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 };=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /*=C2=A0=C2=A0=C2=A0=C2=A0 0 > 172200 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 };=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /*=C2=A0=C2=A0=C2=A0=C2=A0 0 > 172200 */ >=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* size: 172200, cacheli= nes: 2691, members: 1 */ > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* last cacheline: 40 by= tes */ > }; >=20 > As you can see, the size is exactly the same, as are the offsets for > both members raidMap and ldSpanMap. ... this is good enough to prove that the binary before and after is identical and thus there's no change to the structures, which means the risk of accepting the patch is significantly lower. > The trick is that, thanks to the union and __offset_to_FAM, the > flexible-array member raidMap.ldSpanMap[] now appears as the last > member instead of somewhere in the middle. >=20 > So both ldSpanMap and raidMap.ldSpanMap[] now cleanly overlap, as > seems to have been intended. >=20 > (Exactly the same applies for struct MR_DRV_RAID_MAP_ALL) >=20 > I can include this explanation to the changelog text if you'd like. I'll leave it up to Martin, but I think going forwards it would be helpful if you could indicate that you've checked that the binary layout before and after is unchanged and thus the risk of merging the patch is low. Regards, James