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 20C0B342CB0; Thu, 30 Jul 2026 00:56:47 +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=1785373009; cv=none; b=NYHTLqa3N1v/jVXyKb0AsgLvb2FAqcd+gQTWo+99/dgTRL/FSlM+Q5Ltuxhp8N2dVdWZ8hDPiJ3OAU/2Xirlfez9u/GthsDdWh+DtRmhdm4yj2VWMVwKkKO46hN+q2Jh55EIjryMdV7Yp/muyGI5yYI1FDONDJufmn+f/Bo+YnM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785373009; c=relaxed/simple; bh=DtkxkiD9A478HEY8qXBW9Yqy+UvCCvranmkM2sYBcAs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GoyPCiphUCtV1rv68xXIzeaTzsLLao2mS2Xxg94dy+4QEBPce4S3aQb4aw5U57DyumoBZRcfyAu4QTx9jes0CnYnwJ2A/IFiFyc00WCcdvo8GBBjvAbkfCL7EVpJGdipZbySkIC8V4XaW5Yv4nnXb4RyXnpb8F5x4apxq8LXPkw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AohHDmMV; 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="AohHDmMV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AADD1F000E9; Thu, 30 Jul 2026 00:56:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785373007; bh=zt4XsvfQmoUsuB3jF9FwECnRMx4GfwPVJ6if8Bh+4z0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AohHDmMVSo8qU5+ckSCrVwDDNg+tvVhiZXMRDvyWcVXTM80+54bbS9p931iQFK2+A 68Kc/DC+QapwNlrQd0aJF849XvRiXg0ybsM4lafKn3w3bb+0PDybGOrzgN3Qape5Uk AOkl0HkC8SiqoC3caTnbRbxdyc3pPgu4S6gF7qDIIAdRs2VuyBkyeskVVbvg3bhpLM lN5eAgQ2U3YDCoKcIzMPJ0VCAg2VoOzpO30EoNODHtnkVfQwlwKH/zrifSsgBGyvJj /65C9E7dQjw0hTcCXONLr49PuV2W/8ed4X56BRY6u60x+TKzz4HL3ReZUpBmICRSYP t22JHVQNHNxMw== From: SJ Park To: stable@vger.kernel.org Cc: damon@lists.linux.dev, SJ Park , Yang yingliang , Andrew Morton Subject: [PATCH 6.12.y] mm/damon/core: validate ranges in damon_set_regions() Date: Wed, 29 Jul 2026 17:56:39 -0700 Message-ID: <20260730005639.108842-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <2026072900-emit-mortified-8331@gregkh> References: <2026072900-emit-mortified-8331@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 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; + for (i = 0; i < nr_ranges; i++) { + if (ALIGN_DOWN(ranges[i].start, DAMON_MIN_REGION) >= + ALIGN(ranges[i].end, DAMON_MIN_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