From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 A660A4AEBD6 for ; Wed, 16 Sep 2026 10:54:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789556058; cv=none; b=psvvTKsPtwF6SXXZqSWRgITWn5dtaso9hFUXtmrJUhbwk9hJ7qu/4ihBmTWky9HmKx5g8vC+EZhAlK/yFxgnVi2OnzSJ7hfe2COT+J87QeHjnweYjGK0m6VThvMP36XtUBPQzQ2EkT4IcxXcsFVKUllyfjd61xwk04qv13OkbjQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789556058; c=relaxed/simple; bh=JiQPpnjmbnIdMQlQtrteJcQmH6vqbSZ3PSIkpllSQgk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SaZpz66mUNH7l9TtuHQdHuVpduyUoOvp0s47l6mnOZnotr+t7Tc8mNU4wl+F8PRg1CU/2O6G1oj4gzQY7gKMzxBPEPAhvWeIxXGkBTuon3Pb49RfEuDLl9zZOwOhnhxGv6aATUGLhv0xyDtFfV9oj+Dyv5wR0FDsGys/PQe95aQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bSUpKngB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bSUpKngB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E75651F000FF; Wed, 16 Sep 2026 10:53:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789556041; bh=K8sT3qjJgiYU41deN4p7Wl5xM6q6ADoh7h6pB9tDP0M=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bSUpKngBu52G0CG8UQlTQFfbdTiEhxt4kuSWUaDB4z3r4fMrZH5qgTjYirquqN/Kz 5hVYfgVpU9YI32/BjQglTFoDEDl8MrHBwF362ZLSy3cIGdGtah9Y/PIzT6/LuxopqG Cli/VuqBav0YEsey2gCTj/FxMhxHZ1mM6M+4ppEKXSozxCIf2J9R+kcMpX+0VYhpKe nYkINUFpU7ryYS6pE6tVnB1rNTGDsJZm3ABWbDFhkZHOqwgshdRNLj3qbv6gBqTuux rHrXbp6FInlycGD/QQC0s1Azyv7MFlIl5idEq0qit+lWvnQ6Nzi5KYd+JuxCAnG4nd u89xAa8eGHM+w== Message-ID: <27b6a4de-ddc1-4aed-bd30-f466c730d551@kernel.org> Date: Wed, 16 Sep 2026 12:53:57 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5] mm/gup_test: safely calculate GUP batch size To: Sarthak Sharma , Andrew Morton Cc: Jason Gunthorpe , John Hubbard , Peter Xu , Kiryl Shutsemau , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260915102524.125758-1-sarthak.sharma@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/15/26 12:25, Sarthak Sharma wrote: > __gup_test_ioctl() calculates the end of a GUP batch using: > > next = addr + nr * PAGE_SIZE; > > If nr is too large, it can cause next to overflow and wrap around. > If it wraps, the next > end check is bypassed and a large value > of nr is passed to the GUP call, even though the pages array was > allocated according to gup->size. This can lead to out of bounds writes. > > Also, when fewer than PAGE_SIZE bytes remain, the calculated batch > contains zero pages. The code still calls GUP functions with pages + i, > which can point past the allocated array. > > Calculate nr by taking the minimum of the number of pages per call and > the pages remaining in the address range. Reject zero sized and non > page aligned gup->size values and zero nr_pages_per_call value. > > Fixes: 64c349f4ae78 ("mm: add infrastructure for get_user_pages_fast() benchmarking") > Reviewed-by: Kiryl Shutsemau (Meta) > Signed-off-by: Sarthak Sharma > --- Acked-by: David Hildenbrand (Arm) -- Cheers, David