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 45ED13FB07E for ; Wed, 10 Jun 2026 12:21:11 +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=1781094072; cv=none; b=lh+89xPMtEw1Cap6m9FSBngCF0HP8tne0MZNTuto8hJSgDnCC+sTN6cUWSQO81S24ywirYJSQHHUVRp02DZztsbRggvhT+1hBcNPaAO3yLW98LrXbU7NP3pw1eZgjssXr8a1RJ4GZ/kI37ZIzwniJlbxY3QRoZGInT6h/XGTnCg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781094072; c=relaxed/simple; bh=s4688fspE/So3+masoXfwgWtFVmjdaq4LSU8KQHfSqU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oxmB1EO8809roeMdPMZMs+26upoCkX4S71NYD1Wv9y5ri6LWj2J26OjdTqVlAB+xtfp0FK903+VJvmsYaSi1+zt08CQvuPKqAq9jJWszzlHS1q0Gr+LrnOrZ6WN9C1JrsZqlojJB0sOrxW3KWrnVXxSybQDND4TzvRB8x4+bjBI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=akMPVhfx; 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="akMPVhfx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F0F61F00893; Wed, 10 Jun 2026 12:21:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781094070; bh=a50tMtdpQDTnzTpaK5Q8i3OL0e4khg4RGHRIQxs1leQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=akMPVhfxGvtalWUO0OgRsv68Go+o+3t7MAmYT0dp6OsxlUC1e6AyfVLF/sabFbfnm TYXTpQFdV+014B6UOGjc3ykeBPuOXoGqhyV/uYSgobvajXDcfWOgjHEuEKVgennMnd m+3FU4t6Ek223HZamneqahsgsrdoj9VAs15OkTL/cScrnK+YyCVzv70h+1bcx9recK fvG5Rb1K0B/iXM+9VtOS0wpaMe6sI+zLjHtAt3dQPGZ5GJa+JmK4LV+b7lPv0H1R0f Kc7+K0TM7HnZmB8+jOOJVMV6GSxQ10HDMoDy91dVFaJ73aeHm5Oxr5LuJb7+cG52UQ s307kLXL6ywhQ== Message-ID: <33003570-fe67-4c08-ab7c-fdc9f85e2147@kernel.org> Date: Wed, 10 Jun 2026 14:21:06 +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: Andrew Morton , Samuel Moelius 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> <20260609182705.7b3a46e7c4661bd55f8561eb@linux-foundation.org> 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 6/10/26 03:27, Andrew Morton wrote: > On Tue, 9 Jun 2026 00:48:15 +0000 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. >> >> Compute the end address once with overflow checking and use that checked >> end for the loop bounds. >> > > Looks sane, thanks. > >> --- 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)) > > I wonder why those fields were made __u64 instead of ulong. > >> 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; > > Sashiko AI review identified a pre-existing possible overflow here on > 32-bit machines. > > https://sashiko.dev/#/patchset/20260609004814.1240586.6294d614ac80.gup-test-range-end-wrap@trailofbits.com I mean, we don't really care for gup_test.c about any of that. The patch here looks like a decent cleanup, so I think we should take it. Fixing odd things on 32bit that will never happen? Not so sure. -- Cheers, David