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 5335A312825 for ; Thu, 30 Jul 2026 01:15:54 +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=1785374156; cv=none; b=sknenwwzDIJYAcKIQKv2Ip6S96IAyhKJDqby1qk0z5cgPXZHtlYgJ5r4p6UkwnEMZyuV2VT+2V2UMKgDjIGUqhzlnizMfpwa6A2JiXYZ00hwr5pzSESfwJ2gu8fDPhtcvw3T2sHUndqT8mEfKpnIB/5s8xFPQo06Wxs7LcmF1xM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785374156; c=relaxed/simple; bh=TePSwM2PQqqLPNdgGf1q+waVTN8GGs5vA5PKDbBKYGc=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=YU7DHP6CatpqAaR2GfrN8RRGoP4u6Sai49sxZXz7SWgCM81iWdLUMPxJCG03VjJ9zR4weqWASmy9zPM5EUmcUTRFrahoogDtHrmCSMX1Y+sy9Uy5efe1ztGQ9RVQsKD1rN+okAbFKuo918mbzaK5H4rRc8Za+3su//vwBSypGwk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hzdYMHFP; 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="hzdYMHFP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 972251F000E9; Thu, 30 Jul 2026 01:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785374154; bh=Y0cdE7EWSSoRDbAJ3umaZDetYoT9gIjy7C9dAV41CFA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=hzdYMHFPPGStjc1TacvSwph5Oq2aBdZdfqFmtHoqfUtLhJkpCzI2RgajNRkt3nu+l EnaN52egtx0L8c7iZNYIKQjcX7V+EgE5riH6pU0ZyXF2f+MvPFAoGSYk/foEcSGRZZ CM0Pu6qE2lxgsp/A4Ft7YGSa7wW2RbdkCjH9CAYRim3J4mEtaEehkuv/dc0Tv+BZ4G fskj/E2a6oiehiI6YPIXQ41ldsLjN/qmQkWpWz8hFVRC3URXc6roMfr6pQ5kHjkwzI eeg5vcrx+AO3eIm1t1+YjSjYGqAMxOWyQQsYpcnw8HdQPgktG189mkazlB7RLGfloX UePiy7lfGi7xw== From: sashiko-bot@kernel.org Subject: Re: [PATCH 6.12.y] mm/damon/core: validate ranges in damon_set_regions() Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20260730005639.108842-1-sj@kernel.org> References: <2026072900-emit-mortified-8331@gregkh> <20260730005639.108842-1-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 30 Jul 2026 01:15:54 +0000 Message-Id: <20260730011554.972251F000E9@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 3 potential issue(= s) to consider: New issues: - [High] The newly added validation check incorrectly uses alignment macros= , allowing unaligned zero-length or inverted regions to silently bypass val= idation. - [Medium] The validation check unconditionally rejects valid monitoring ra= nges ending near the top of the address space due to an integer overflow in= the ALIGN macro. Pre-existing issues: - [High] Alignment rounding combined with a flawed iteration loop creates o= verlapping monitoring regions from valid, non-overlapping user inputs. -- --- Patch [1]: [PATCH 6.12.y] mm/damon/core: validate ranges in damon_set_r= egions() --- commit b519271ef73c8bbed5092bcf809ea6bc504693b6 Author: SJ Park Date: Thu Jul 30 00:56:39 2026 +0000 mm/damon/core: validate ranges in damon_set_regions() =20 This commit attempts to validate regions in damon_set_regions() to reject=20 zero length monitoring target regions, which could previously trigger a=20 divide-by-zero or WARN_ONCE. Link: https://lore.kernel.org/20260630035221.146458-1-sj@kernel.org > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 7911599c37f22..7217bb2ef51ec 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -214,6 +214,12 @@ int damon_set_regions(struct damon_target *t, struct= damon_addr_range *ranges, > unsigned int i; > int err; > =20 > + for (i =3D 0; i < nr_ranges; i++) { > + if (ALIGN_DOWN(ranges[i].start, DAMON_MIN_REGION) >=3D > + ALIGN(ranges[i].end, DAMON_MIN_REGION)) > + return -EINVAL; > + } > + [Severity: High] Does this validation logic allow unaligned zero-length or inverted regions to bypass the check? If a user configures an unaligned empty region (e.g., start =3D 4097,=20 end =3D 4097) via sysfs, ALIGN_DOWN evaluates to 4096 and ALIGN evaluates to 8192. The condition 4096 >=3D 8192 evaluates to false, which completely=20 bypasses the rejection of the invalid region. [Severity: Medium] Will this check unconditionally reject valid monitoring ranges ending near = the top of the address space? If a caller specifies a monitoring region ending near ULONG_MAX, the ALIGN(ranges[i].end, DAMON_MIN_REGION) operation could wrap around to 0. This would cause the unsigned comparison ALIGN_DOWN(start) >=3D 0 to always evaluate to true, resulting in a false positive -EINVAL rejection. [Severity: High] This is a pre-existing issue, but does alignment rounding combined with the iteration loop create overlapping monitoring regions from valid, non-overlapping user inputs? mm/damon/core.c:damon_set_regions() { ... if (!first) { /* no region intersects with this range */ newr =3D damon_new_region( ALIGN_DOWN(range->start, DAMON_MIN_REGION), ALIGN(range->end, DAMON_MIN_REGION)); if (!newr) return -ENOMEM; damon_insert_region(newr, damon_prev_region(r), r, t); } else { ... } If a user configures adjacent, non-overlapping unaligned ranges (e.g.,=20 start =3D 0, end =3D 4097 and start =3D 4098, end =3D 8192), ALIGN_DOWN and= ALIGN=20 expand these to [0, 8192] and [4096, 8192], which overlap. Furthermore, because the loop cursor is not reset, intersection checks are= =20 skipped for subsequent ranges once the list end is reached. Could this caus= e=20 these overlapping regions to be blindly inserted, potentially corrupting=20 core data structures? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260730005639.1088= 42-1-sj@kernel.org?part=3D1