From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) (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 9950380632 for ; Thu, 9 May 2024 21:24:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.58.85.151 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715289842; cv=none; b=kiPy/07Cc65kyMBMbwOSE5DrpxEh5zq03/Q94Jhgga4KGVVzbjTgizCoHtguusZ5kYZfCvkaKyVUzCYlD3mmQ6xiEwxbvMBB8Ldd0dcb7TdkyvU4uAuLfxnEEQQjJybvl6Ou5choL9cWpn8QRHUxoTShHdh0kel2GOqumdzcX68= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715289842; c=relaxed/simple; bh=SEFpFTBcxfnU5YKbgVM3TPjMbGxapd0haMRAIoOJewg=; h=From:To:CC:Subject:Date:Message-ID:References:In-Reply-To: MIME-Version:Content-Type; b=QjCTnxQEQ150bS+d1uoaiPo991ULIhWRNWS/B/l0SvMrwEQx5oUmKXq1hlZfphnWYUqFvfN3Bl8/5muMBX1EVe/7aARz/rITeWd1j/kZPzLLScXFPQ99Qk8PPUPHOjDndPOmBK983H22Ku0rwol9/S3/x35Z9lRoHyX/5cBfia4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ACULAB.COM; spf=pass smtp.mailfrom=aculab.com; arc=none smtp.client-ip=185.58.85.151 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ACULAB.COM Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=aculab.com Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-262-ZHxZcEbrMxKlg_Jm_e8yvA-1; Thu, 09 May 2024 22:23:57 +0100 X-MC-Unique: ZHxZcEbrMxKlg_Jm_e8yvA-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Thu, 9 May 2024 22:23:29 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.048; Thu, 9 May 2024 22:23:29 +0100 From: David Laight To: 'Linus Torvalds' , Kees Cook CC: Justin Stitt , Peter Zijlstra , Mark Rutland , "linux-hardening@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "llvm@lists.linux.dev" Subject: RE: [RFC] Mitigating unexpected arithmetic overflow Thread-Topic: [RFC] Mitigating unexpected arithmetic overflow Thread-Index: AQHaoaITK91jQ1nmYEmzGISNIfAGlrGPZyIw Date: Thu, 9 May 2024 21:23:29 +0000 Message-ID: References: <202404291502.612E0A10@keescook> <202405081144.D5FCC44A@keescook> <202405081354.B0A8194B3C@keescook> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 Li4uDQo+IEkgdGhpbmsgdGhhdCB3b3VsZCBiZSBhIGNvbXBsZXRlbHkgZGlmZmVyZW50IGFyZWEg dGhhdCBtaWdodCBiZSB3b3J0aA0KPiBsb29raW5nIGF0OiBpbnN0cnVtZW50aW5nIGltcGxpY2l0 IGNhc3RzIGZvciAiZHJvcHMgYml0cyIuIEknbSBhZnJhaWQNCj4gdGhhdCBpdCdzIGp1c3QgKnNv KiBjb21tb24gdGhhbiB3ZSBtaWdodCBub3QgYmUgYWJsZSB0byBkbyB0aGF0DQo+IHNhbmVseS4N Cg0KVGhpbmdzIGxpa2U6DQoJYnVmWzBdID0gdmFsOw0KCWJ1ZlsxXSA9IHZhbCA+Pj0gODsNCgli dWZbMl0gPSB2YWwgPj49IDg7DQoJYnVmWzNdID0gdmFsID4+PSA4Ow0KZm9yIHdyaXRpbmcgYSB2 YWx1ZSBsaXR0bGUtZW5kaWFuIGFuZCBwb3RlbnRpYWxseSBtaXNhbGlnbmVkLg0KUmVhbGx5IGRv ZXNuJ3Qgd2FudCBhbnkgYW5ub3RhdGlvbi4NCg0KSSd2ZSBhbHNvIHNlZW4gY29kZSBsaWtlOg0K CWJ1ZlswXSA9ICh1bnNpZ25lZCBjaGFyKSh2YWwgJiAweGZmKTsNCm5vdCBvbmx5IHVnbHkgYnkg aXQgZ290IGNvbXBpbGVkIHRvOg0KCXZhbCAmPSAweGZmIC8vIGZvciB0aGUgJg0KCXZhbCAmPSAw eGZmIC8vIGZvciB0aGUgY2FzdA0KCWJ5dGUgd3JpdGUgdG8gbWVtb3J5Lg0KTW9kZXJuIGdjYyBk b2Vzbid0IGRvIHRoYXQsIGJ1dC4uLg0KDQpUaGVyZSBhcmUgc29tZSBzcHVyaW91cyBjYXN0cyB0 aGF0IGRyb3AgYml0cy4NCkkgZm91bmQgcGxlbnR5IG9mIGR1YmlvdXMgbWluX3QodTgvdTE2LC4u LikgZXhhbXBsZXMuDQooV2VsbCB0aGV5IGFyZSBkdWJpb3VzLCBzb21lIGFyZSBqdXN0IGEgbG90 IG1vcmUgZHViaW91cyB0aGFuIG90aGVycy4pDQpUaGUgcHJvYmxlbSBpcyB0aGF0IGV2ZXJ5IG9u ZSBuZWVkcyBjYXJlZnVsIGluc3BlY3Rpb24ganVzdCBpbiBjYXNlDQp0aGUgc3RyYW5nZSBiZWhh dmlvdXIgaXMgcmVxdWlyZWQgbGlrZSBtaW5fdCh1OCwgdmFsIC0gMSwgbG9fbGltIC0gMSkNCndo aWNoIHRyZWF0cyBsb19saW0gb2YgemVybyBhcyAnbm90IGEgbGltaXQnIGFuZCBJIHRoaW5rIHdh cyBvay4NCg0KQSBzbG93LCBjb25jZXJ0ZWQgZWZmb3J0IHRvIHJlbW92ZSBtaW5fdCgpIGNhbGxz IHdvdWxkbid0IGJlIGEgYmFkIHRoaW5nLg0KDQoJRGF2aWQNCg0KLQ0KUmVnaXN0ZXJlZCBBZGRy ZXNzIExha2VzaWRlLCBCcmFtbGV5IFJvYWQsIE1vdW50IEZhcm0sIE1pbHRvbiBLZXluZXMsIE1L MSAxUFQsIFVLDQpSZWdpc3RyYXRpb24gTm86IDEzOTczODYgKFdhbGVzKQ0K