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 53DB1275870; Thu, 30 Jul 2026 00:59:26 +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=1785373167; cv=none; b=gN37d/nS2xhFyLQUmzbGb/XAKyRBRWmC6No6xxVHHn4zw1BNB2BXXiQgjjuOpHxhQvj1x6Pe+UuKtB/PKsIBzKP5IoMeVXqrE4cQf4CbUVzxqUQhViuGvFKcUeyp0Nf5dfDWFoNTSMeCc82YfJRjMGoHuf1be6QptNs0bKRky3A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785373167; c=relaxed/simple; bh=5+cYsASVRh2uLBQTCYu+3wxiDdOSO1Zvl+UX68Gxqo0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rN1oNBUS9/1zJELiWC1eyb2ZQcUdO3Qqarxi3k1ueVGYk4TWEdSr2LvJJHDwY8ruvdYpL2sQ+I7+2U2SjZrQVPmgKyZAdwz0k/7zRt0aK7BXvZmv/ivD35jVNifGO/1NJwG1eoCDnLZEcEwpebFYXBROa441od2EPWSTjgLGego= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AD/B4nfw; 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="AD/B4nfw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA5701F000E9; Thu, 30 Jul 2026 00:59:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785373165; bh=He/ha+AKaBGNbMo5KBtIDX7c4iKcLwK62YpnNkglYUk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AD/B4nfwcgL3Itt3WHZvtuOOvZUTpkORXKeX+R9qopwgJQgBjnk+mTfS0uQecVgR1 y+PPtzvn0ZztKE6KjvxFNgEyIfeP5jFnehelWt1ubkNc7XMloC3IYunIcO6MHJp0kc I4C88RP/BM8xFXy1oNwYP4QLJaPs6c6r8j/nYFK10igD8nzF8KND+Pkf9uJzs8dTcv P6FM+c82rSlPRgBEpmd3GmOESkGYyCodxox6sxkyz9uztG7iR1zD9jKRafoF15Qa0r DD0i0UBnJ5nQ3D6usAKuA1/LfDf+Gh+h3LktN65TAa3plVfwk1n4mCufZhEccav8wI dJjNx7aC8ngHw== From: SJ Park To: stable@vger.kernel.org Cc: damon@lists.linux.dev, SJ Park , Yang yingliang , Andrew Morton Subject: [PATCH 6.6.y] mm/damon/core: validate ranges in damon_set_regions() Date: Wed, 29 Jul 2026 17:59:17 -0700 Message-ID: <20260730005917.112632-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <2026072901-unmarked-salvage-c2a5@gregkh> References: <2026072901-unmarked-salvage-c2a5@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 46600265d7ffc..437a52fd6e0ee 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -212,6 +212,12 @@ 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