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Wed, 26 May 2021 12:21:25 -0700 (PDT) Received: from ziepe.ca ([206.223.160.26]) by smtp.gmail.com with ESMTPSA id 127sm2172724qkl.116.2021.05.26.12.21.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 12:21:24 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1llz5n-00FI2b-Re; Wed, 26 May 2021 16:21:23 -0300 Date: Wed, 26 May 2021 16:21:23 -0300 From: Jason Gunthorpe To: Colin King Cc: =?utf-8?B?SsOpcsO0bWU=?= Glisse , Andrew Morton , Ralph Campbell , Stephen Rothwell , Alistair Popple , linux-mm@kvack.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][V2][next] mm: selftests: fix potential integer overflow on shift of a int Message-ID: <20210526192123.GE1096940@ziepe.ca> References: <20210526170530.3766167-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210526170530.3766167-1-colin.king@canonical.com> X-Rspamd-Queue-Id: C174E2C7 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b="SM3f/vu2"; dmarc=none; spf=pass (imf20.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.160.174 as permitted sender) smtp.mailfrom=jgg@ziepe.ca X-Rspamd-Server: rspam03 X-Stat-Signature: 5zmq5x4kwjpm1zyannyrosgeopyhq5zq X-HE-Tag: 1622056876-842488 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: On Wed, May 26, 2021 at 06:05:30PM +0100, Colin King wrote: > From: Colin Ian King > > The left shift of the int mapped is evaluated using 32 bit arithmetic > and then assigned to an unsigned long. In the case where mapped is > 0x80000 when PAGE_SHIFT is 12 will lead to the upper bits being > sign extended in the unsigned long. Larger values can lead to an > int overflow. Avoid this by making mapped an unsigned long. > > Addresses-Coverity: ("Uninitentional integer overflow") > Fixes: 8b2a105c3794 ("mm: selftests for exclusive device memory") > Signed-off-by: Colin Ian King > --- > > V2: Make mapped an unsigned long rather than casting it to unsigned long Reviewed-by: Jason Gunthorpe Jason