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 07F57223DCE; Sat, 27 Jun 2026 17:01:06 +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=1782579668; cv=none; b=UvRSQIuWrY+8W9hSmtqtIoJ2Xm44fpOVDjP/nI+Iu8jiLd9ENGDsU/banqfEdWv4/m4biO8pPiKI47ZfPUVfSCcoThJHRGjn0/d8j3u2RZZ9BC2hocFbcas2oJn3wdrNcjjVDvVZLfYOrpfcE6KKbGU05eRhh1swHkKo1iTAj+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782579668; c=relaxed/simple; bh=TulduVJ3UOJV8TsyJ7ffk1l75Pt4FkT2/HyvATqxan4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=JC1Adp5X5OhnQBBuXZ8wM/SpWDHO4CCPRmfCtwjbAfckru0vWUKIECQ5d/YhFT2NRzEoZFdyQtsnlbKAgBtJqrZLCLv1s41YU6DoSxWTON3tAshTbVHo7HbII5GveYnNBDQa5TdXlkBG86UmXdkAJgRvXguG/Jnkaq7LzF8bp4Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PesMaXNu; 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="PesMaXNu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55E9F1F000E9; Sat, 27 Jun 2026 17:01:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782579666; bh=hEn2zn5pWhG25VPBcYCkS7+7B1NjobplNjZ+d8XjyHk=; h=From:To:Cc:Subject:Date; b=PesMaXNupjJJGZuvo+yqSgEunZs+pIOijrjAHoAz5KrDeHs0eigW5qDmImhC3o89x 3b05rCW3a4MZW5+hrLKEXgTaI6tudKUTTVvihDNtu3HdxuR1GuIj2Mzxgr6RiY1SWh MsmNSEeCYz2UitAgd6o8IWpfmoVHW0ELS1mJAMEDeDOzBRoNaW4L14iN1um4STbEmJ Rm6tlfZuBEb4TplCTLPpgBz2BYti0F6F65IB9CEOdRVIlh1MPC7NU+uakrRCaYMKC2 vxE+vucgP/CpLxAX0vYqKHLzaVSul7ngSaIxty8mvzcKvekNwYDXW7dmjT+X5k3KoU FpI7CLVly3dqw== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , Yang Yingliang , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org Subject: [RFC PATCH] mm/damon/core: validate ranges in damon_set_regions() Date: Sat, 27 Jun 2026 10:00:56 -0700 Message-ID: <20260627170057.1867-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 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 [...] Disallow empty region user inputs by updating the validation logic. Fixes: 43b0536cb471 ("mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)") Cc: # 5.16.x Signed-off-by: SeongJae Park --- mm/damon/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/damon/core.c b/mm/damon/core.c index 7e4b9affc5b06..b3100d7fa5596 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -358,6 +358,11 @@ 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 (ranges[i].start >= ranges[i].end) + 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++) { base-commit: f5cde2d41633df3fb1965efa00bfa827ca41836c -- 2.47.3