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Wed, 29 Nov 2023 11:42:48 +0800 Received: from mszsdtlt102.gcn.mediatek.inc (10.16.4.142) by mtkmbs13n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1118.26 via Frontend Transport; Wed, 29 Nov 2023 11:42:48 +0800 From: Haibo Li To: CC: , , , , , , , , , , , , , , Subject: Re: [PATCH] fix comparison of unsigned expression < 0 Date: Wed, 29 Nov 2023 11:42:47 +0800 Message-ID: <20231129034247.226365-1-haibo.li@mediatek.com> X-Mailer: git-send-email 2.34.3 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-TM-AS-Product-Ver: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-AS-Result: No-10--15.269300-8.000000 X-TMASE-MatchedRID: L8tZF6zWW2q0m/IROg5s5fHkpkyUphL9HTzSJQBZgdFqI8duabhZa/79 6l+IAtl+w8XU8bLzT9L5qR7J2CotBvww9Stut6YHmNvbnzNu6oLTDXgcUlCNowFbHA9TqNLQmtk ZkOzLak8jjoep8ZitK6EZtwWhhaEgAYINegaglbBc/msUC5wFQX4rryovYbmmQ4pQeOTu+8UY20 f1wrB11n4I3WRiw3QYqULTfmF5uZHqi7LDVhVKr51U1lojafr//5QRvrl2CZCo+b+yOP0oGFC9o pMYDUg2585VzGMOFzA9wJeM2pSaRbxAi7jPoeEQftwZ3X11IV0= X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--15.269300-8.000000 X-TMASE-Version: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-SNTS-SMTP: 9998098F6E1CA8C593C63DD30B494B533A460EDFA2BA4999AF9EE84F9D7D46BD2000:8 X-MTK: N X-Rspamd-Queue-Id: 53A961C000D X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: hez57xijfdboryxc9mscy4hpyxtkgm9n X-HE-Tag: 1701229387-220912 X-HE-Meta: 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 uS/a/EsW fgw/RFsoqxQKSmH6ZPrwv3XZ3jJOHWY/Z5PVS6XzitkxxyXbsCKafUYPuTTTaL7zLBp9VWpIbdyf7Enrcve5wXXK4jf3Lfw2DIarTEG44Ped4oFJPYjsXLGIYhavNW/X7d5OU5acv37qSKgwoGLfkLtrpxpBwKEEqKo1LUH+ljY4A+fDas1PPo8WSohv7GUqHTvNfma6fRKfFjO1BT7UoCaKygxtN+l+kJrYE+9JsrM30JqfsPFtj4Aci0THnyIYtIjkTApLd6y7CSYKRZ9qRdtyjy+rRdAI17qSu+XgCm1XMMe/6Ujs/CBEZKvO+REnL5ab3FU9A8tOVEKBrqozhSKPZZeUkMgkyylREUJvwFKHeva9GX2DnFr00tsAvb20BocqNg3is7v+clnIO3z0NQBOQn/3Reah/yfvDl9lqtRp/YPJXhPrT5ztnduipmfbCvSSSkbwyL8c+fMxN2cQCfIQsQw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > On Wed, Nov 29, 2023 at 2:22 AM Andrew Morton wrote: > > > > On Tue, 28 Nov 2023 15:55:32 +0800 Haibo Li wrote: > > > > > Kernel test robot reported: > > > > > > ''' > > > mm/kasan/report.c:637 kasan_non_canonical_hook() warn: > > > unsigned 'addr' is never less than zero. > > > ''' > > > The KASAN_SHADOW_OFFSET is 0 on loongarch64. > > > > > > To fix it,check the KASAN_SHADOW_OFFSET before do comparison. > > > > > > --- a/mm/kasan/report.c > > > +++ b/mm/kasan/report.c > > > @@ -634,10 +634,10 @@ void kasan_non_canonical_hook(unsigned long addr) > > > { > > > unsigned long orig_addr; > > > const char *bug_type; > > > - > > > +#if KASAN_SHADOW_OFFSET > 0 > > > if (addr < KASAN_SHADOW_OFFSET) > > > return; > > > - > > > +#endif > > > > We'd rather not add ugly ifdefs for a simple test like this. If we > > replace "<" with "<=", does it fix? I suspect that's wrong. > > Changing the comparison into "<=" would be wrong. > > But I actually don't think we need to fix anything here. > > This issue looks quite close to a similar comparison with 0 issue > Linus shared his opinion on here: > > https://lore.kernel.org/all/Pine.LNX.4.58.0411230958260.20993@ppc970.osdl.org/ > > I don't know if the common consensus with the regard to issues like > that changed since then. But if not, perhaps we can treat this kernel > test robot report as a false positive. > > Thanks! Thanks for the information.Let's keep it as unchanged.