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 7A75E296BCB; Thu, 30 Jul 2026 00:51:55 +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=1785372716; cv=none; b=rMSgXd3dM6e96ZbKjGz9QlD1YObhUiVrnpNSQE3GFBX/erYJ6v3zrlqRWfypbN761USEBvov4Cnc0yjGToYdsWpqSstrAFTtIsa6XkoYADjReRI3IVt88nYVkcW+zyXcOlJIzlRwTFyRhrFxHZ1W1CW2shm5Q6nMbGJxXF8y1mE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785372716; c=relaxed/simple; bh=NqC+RkPF8N9pixYdSt3w85V44GE1evqWTXImUv2vySs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tSJ6NGDZZd0MWg+lpELDMxA5slti7wKMX5YcBICZ4tInnqPu14mxfReuXRiMYilqi/y0ALWbN1wJoASdnUCtTiK5IB51vEQOEl3TDY483a3gp5VWKU6mWNUZZRdOPDf/16QxzhysiGnjoYrZs/sclz31fQd00eIMPt2uGcgdoaw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PEsQ5yjM; 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="PEsQ5yjM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8ECA1F00A3A; Thu, 30 Jul 2026 00:51:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785372715; bh=KOkTBSVx3hc9Wg8+80vwysBoAd9JkHnFQUKihMYqscM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PEsQ5yjMCKU2wNJ5c8J4nAPL0CN2WHom5KxZIHuYOkkLcy/Zm9E1y92eHijNfeek7 ZnfHzNfHOQUK6Lq7fAX1RPWSao93r1zlMvXo+VekARTF/wy3iZ6sY01+xDn7TaTjN8 rclie75jvQ4sSoImg54CTXDXYJgoBJlGZ+4W7fvStNA23QvWUP6lU/tWuJfjmXUluW JvBFt64/rGHSGJqSf6CO6tMfI6AYh0tjSqVBmwbElGM1j+oWS+E9oHJgLjP4uYRYM2 GhJecqrdcEWKZQzwZ6yYLRo2UEIe6GRRp8epw7DjOPpwU7mRM9sCAnKwEmrW3GueHq mykzFSkv7fSyA== From: SJ Park To: stable@vger.kernel.org Cc: damon@lists.linux.dev, SJ Park , Yang yingliang , Andrew Morton Subject: [PATCH 6.18.y] mm/damon/core: validate ranges in damon_set_regions() Date: Wed, 29 Jul 2026 17:51:45 -0700 Message-ID: <20260730005145.104960-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <2026072900-remedial-nectar-f412@gregkh> References: <2026072900-remedial-nectar-f412@gregkh> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit DAMON core logic assumes zero length regions don't exist. However, a few DAMON API callers including DAMON_SYSFS, DAMON_RECLAIM and DAMON_LRU_SORT allow users to set empty monitoring target regions. This could result in WARN_ONCE() on CONFIG_DAMON_DEBUG_SANITY enabled kernel, and divide-by-zero from damon_merge_two_regions(). For example, the WANR_ONCE() can be triggered like below. # grep DAMON_DEBUG_SANITY /boot/config-$(uname -r) # CONFIG_DAMON_DEBUG_SANITY=y # damo start # cd /sys/kernel/mm/damon/admin/kdamonds/0 # echo 0 > contexts/0/targets/0/regions/0/start # echo 0 > contexts/0/targets/0/regions/0/end # echo commit > state # dmesg [....] [ 73.705780] ------------[ cut here ]------------ [ 73.707552] start 0 >= end 0 [ 73.708452] WARNING: mm/damon/core.c:359 at damon_new_region+0x6e/0x80, CPU#1: kdamond.0/758 [...] All DAMON API callers eventually use damon_set_regions() to setup the regions. Add the validation logic in the function. Link: https://lore.kernel.org/20260630035221.146458-1-sj@kernel.org Fixes: 43b0536cb471 ("mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)") Signed-off-by: SJ Park Cc: Yang yingliang Cc: # 5.16.x Signed-off-by: Andrew Morton (cherry picked from commit 1292c0ecb1caefb8ca064a3639d5673991e8810c) Signed-off-by: SJ Park --- mm/damon/core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 3e221c888e302..4ab1ed472fbcc 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -215,6 +215,12 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, unsigned int i; int err; + for (i = 0; i < nr_ranges; i++) { + if (ALIGN_DOWN(ranges[i].start, min_sz_region) >= + ALIGN(ranges[i].end, min_sz_region)) + return -EINVAL; + } + /* Remove regions which are not in the new ranges */ damon_for_each_region_safe(r, next, t) { for (i = 0; i < nr_ranges; i++) { -- 2.47.3