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 ABD821B4F1F for ; Wed, 1 Jul 2026 16:22:21 +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=1782922942; cv=none; b=ourM/5k7Wo8CzKIIamueRKR38cjciLJKiIglOR0ztJHUVfRpWqJzhXnzoY7ct+DGQx8c7XUVOLdmylpZthDAqaa5LG3ioy41FnhKzW/JcZxoGB5pliODgyNL9rD++XmUjdeXcmCX2f+VyOBfEfTvO5awfKqF7+RzQdtpRERjtgY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782922942; c=relaxed/simple; bh=p3q2wHA5Ha6oO9QPusIcVIkdaP4RUdM60l0j1pyjejE=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=hIIHXMFj4Ayh/mcpfzO37iuhJIX8Hfycbks7cVhIEoRDw8wPYTzRBFO0074wROcYq5+oiTJ0dzTdHGWcB6JpZ/NyTNqFfD2DHraREG+x2D5lQUJ1fZ20D7HZcZAV1496RmFh8TeJ1xjt7r/qjmpf/Xh1SU9dLgpTFymD37+LCsM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cL3lCWKe; 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="cL3lCWKe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 370651F000E9; Wed, 1 Jul 2026 16:22:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782922941; bh=NpV+qYrVX6WQJiHZbWV8rOmv1LQ0hPH7+29ByflHJgM=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=cL3lCWKeAMz7rfKDPqPYYe9h/KB7+vJOCXPpAa+TTB4yhbjmvcbzW7iVUz0sZo4VV ZDAVGGOA8AqrUXiRsGpD0hsQit3acmDVZd/DcXKnNwAol35rzP24wtOYhkf0HMT9KH xuc/dvHPC7spzgczAv+qMhfqPs5Q0A6Ohr0/zBXxnl3KJR7lHcjHQimbtrfKl1oYSy P/m1FbfiFsgFXwanfWKc6KzmWy0pgZc1oRNsSjo01+G9G8KI4bDz61h1ajqfWp5Jaf 96Hh2kDv/DkY5X6CmbBHSRxDeisJoRuPpUfcWhGsnVcov3EXjpH+2M3n937Dzo+416 5r5bEIWn+QjzA== From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH 7/8] mm/damon/core: remove start, end check in damon_set_region_system_rams() Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20260701144815.113325-8-sj@kernel.org> References: <20260701144815.113325-1-sj@kernel.org> <20260701144815.113325-8-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 01 Jul 2026 16:22:20 +0000 Message-Id: <20260701162221.370651F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [High] Removal of bounds validation permits inverted regions (start > end= ), leading to a massive integer underflow and guaranteed OOM kernel panic. -- commit 03335779d391504c4265be49dedb155969cf1a7d Author: SJ Park mm/damon/core: remove start, end check in damon_set_region_system_rams() This commit removes the explicit start > end validation in damon_set_region_system_rams_default(), stating that damon_set_regions() already performs a complete check. > diff --git a/mm/damon/core.c b/mm/damon/core.c > index ace202f47dd7c..f491a76c98bfc 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -3794,9 +3794,6 @@ int damon_set_region_system_rams_default(struct dam= on_target *t, > { > struct damon_addr_range addr_range; > =20 > - if (*start > *end) > - return -EINVAL; > - [Severity: High] The commit message states that the complete check is done inside damon_set_regions(), but does damon_set_regions() actually validate that start is less than or equal to end? Looking at damon_set_regions(), it appears to blindly create the region with underflowed sizes if start > end: mm/damon/core.c:damon_set_regions() { ... r =3D damon_new_region( ALIGN_DOWN(ranges[i].start, min_region_sz), ALIGN(ranges[i].end, min_region_sz)); ... } If an inverted region (e.g., [4096, 0)) is passed in, could this lead to a massive integer underflow? The size of the region would underflow to roughly ULONG_MAX. Later in damon_apply_min_nr_regions(), this underflow seems to translate into an effectively infinite loop: mm/damon/core.c:damon_apply_min_nr_regions() { ... while (damon_sz_region(r) > max_region_sz) { damon_split_region_at(t, r, max_region_sz); r =3D damon_next_region(r); } ... } Could this loop exhaust system memory by attempting to allocate quadrillions of regions and cause an OOM kernel panic? > if (!*start && !*end && > !damon_find_system_rams_range(start, end, addr_unit)) > return -EINVAL; --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260701144815.1133= 25-1-sj@kernel.org?part=3D7