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 528523AFD08 for ; Wed, 10 Jun 2026 12:18:37 +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=1781093918; cv=none; b=ltMyLwtsMh4wKdvki1a6LFKCAp9iZ43kruaSgVFJHyQoU33VQQ+IeqOF537NNq24ebqjSsfWZ4xS2wwcl8x9bXfykz9B0Cf+jipYawogLAl59cy0iziy3nzsTRhCTMQJqhDsCJIpX7m5KJ8/9WNaBb4FxdR8eg0If6y2d8MrETw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781093918; c=relaxed/simple; bh=fPIMtnIbIgJZTugibiD64u+e9oGKR8xcKx2wa/vPwrs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=pvA8DYPt7YNtLvY/7eJWJvVoXLzl2oANjRj8k1UTcgcWRhAVt38txh38a14l3awU23Usobpy7B0HOp9/ioh+7KEXOwTRjnBTgVlTsLLImhqRFCoGofLS6YrFV5WxmuMaiu84zSwDbyVcdm9aKKu46r1SrBjbGrYIpVz4lk+YyNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jMOXA8GH; 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="jMOXA8GH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68A981F00893; Wed, 10 Jun 2026 12:18:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781093917; bh=A/nmKCF3PlHtsp8BoIrnN8jgGS3KEpCp0NRU8EXhq3c=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=jMOXA8GH07QhcMhyvYrDmhrTiwuzZdFOFsw6UOyGLBIL/AyIsle0E/ksi4Ir8BMtJ 0w0lsgWx/FlQlZon7VbUS2DLTEd87ZIeDUuifkhcshfeZi3hzakJMP7A89qkYTMpYu EMpaGOIEj6y469m44xy6EDVh7+0oY0eMY6bDDg8VrOqlos9uZwYGTPKIrtaKkX/+cB Xgo17v8axIMsXMZy498yaCjQJXJiovxlljAIGiRNXKWiF/gFHjDp/K7aYlPE4NSv/K vODFoFcBsYyGX7YfcMs96aNJlDauvjGwyAaR/H6pbrARFZsRx80zE6bNNQ8PQEH/on pYM1Idh4qADTQ== Message-ID: <05a8071f-d3e7-4a24-985a-41fd5639c8e3@kernel.org> Date: Wed, 10 Jun 2026 14:18:32 +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] mm/gup_test: reject wrapped user ranges To: Samuel Moelius , Andrew Morton Cc: Jason Gunthorpe , John Hubbard , Peter Xu , "open list:MEMORY MANAGEMENT - GUP (GET USER PAGES)" , open list References: <20260609004814.1240586.6294d614ac80.gup-test-range-end-wrap@trailofbits.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 6/9/26 02:48, Samuel Moelius wrote: > gup_test accepts an address and size from the debugfs ioctl and > repeatedly compares against addr + size. If that addition wraps, the > loop can be skipped and the ioctl returns success with size rewritten to > zero. Yeah, it's only used for testing and (a) not expected to be included in production kernels or of so (b) only accessible to root. So we didn't particularly care about making this interface watertight. > > Compute the end address once with overflow checking and use that checked > end for the loop bounds. > > Assisted-by: Codex:gpt-5.5-cyber-preview > Signed-off-by: Samuel Moelius > --- > mm/gup_test.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/mm/gup_test.c b/mm/gup_test.c > index 9dd48db897b9..eb4c9cda16ed 100644 > --- a/mm/gup_test.c > +++ b/mm/gup_test.c > @@ -105,11 +105,15 @@ static int __gup_test_ioctl(unsigned int cmd, > unsigned long i, nr_pages, addr, next; > long nr; > struct page **pages; > + unsigned long end; > int ret = 0; > bool needs_mmap_lock = > cmd != GUP_FAST_BENCHMARK && cmd != PIN_FAST_BENCHMARK; > > - if (gup->size > ULONG_MAX) > + if (gup->addr > ULONG_MAX || gup->size > ULONG_MAX) > + return -EINVAL; > + if (check_add_overflow((unsigned long)gup->addr, > + (unsigned long)gup->size, &end)) > return -EINVAL; > > nr_pages = gup->size / PAGE_SIZE; > @@ -125,13 +129,13 @@ static int __gup_test_ioctl(unsigned int cmd, > i = 0; > nr = gup->nr_pages_per_call; > start_time = ktime_get(); > - for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) { > + for (addr = gup->addr; addr < end; addr = next) { > if (nr != gup->nr_pages_per_call) > break; > > next = addr + nr * PAGE_SIZE; > - if (next > gup->addr + gup->size) { > - next = gup->addr + gup->size; > + if (next > end) { > + next = end; > nr = (next - addr) / PAGE_SIZE; > } > LGTM Acked-by: David Hildenbrand (Arm) -- Cheers, David