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 2958E43C7B4; Thu, 30 Jul 2026 14:49:18 +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=1785422959; cv=none; b=n3wTAWeSBzYjilmGNo9tcAUxDqJKeisZlfBCJ0uYM4lNceAA9YB6oqE2AodezFKErwQrmBMnh6iEoK4hU3YAicGEOS8Hihq0LO62Giz5bjqrmHW/x2uZhZXeqFSQAxjCgqHQM5Z+ovSV5JTKPtNGOyImvqmBwO/qezpyOC2uxP8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785422959; c=relaxed/simple; bh=vWZjDjc1GHVXi7wHc7HnGa1c1BKCnLzgP7eR4RhruLc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RQErh99jO6VLp5XcZQTiypVinGJP+2sB7T8RA+PtLmStlh4Tia/QPz/zKOGQkf2OJ1VPFqVO6h2Jb+dwAYH3eUpOl1xj2A2gDonkxvmawz1UGvjZfSVXGcOIkLaJpXsnMGilN63z5iTwU3VbCkRz0fVuhTcRLYNSNj6+lFmlzVU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=teoTn8sZ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="teoTn8sZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84A3F1F000E9; Thu, 30 Jul 2026 14:49:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785422958; bh=wn6rQduIUW8R0LwXF93DDrI5Cxk+w9FhgLtGqDmcIyY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=teoTn8sZfLy6Gfj2ojA+ZZsJ/7dfD/2QHoow2puteK+4JDRbDAG0vDPv9K6ZoDO+j g9/o5QXCAxGBZ84TgsfoRcfGPEbFh8LfQyK6IYPjkc2bOEiidGR4xUkN2sNUIBDN67 irVjW70EuzetfNXcfRenYOYvBi1Bk0Q1H2XmvXwA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, SJ Park , Andrew Morton Subject: [PATCH 7.1 617/744] mm/damon/core: disallow overlapping input ranges for damon_set_regions() Date: Thu, 30 Jul 2026 16:14:50 +0200 Message-ID: <20260730141457.388242478@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: SJ Park commit 954157679ec34661c2e87e7eb796104a797c32db upstream. damon_set_regions() assumes the input ranges are sorted by the address and don't overlap each other. Hence the assumption was initially to be explicitly validated. But commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting") has mistakenly removed the validation. This can make DAMON behave in unexpected ways. At the best, the monitoring results snapshot will just look weird since there will be overlapping regions. DAMOS will also work weirdly, applying the same action multiple times for overlapping regions, and make DAMOS quota weird. More seriously, depending on the setup and regions updates sequence, negative size regions can be made. It will trigger WARN_ONCE() if the kernel is built with CONFIG_DAMON_DEBUG_SANITY=y. Depending on the monitoring results, the negative size region can further trigger division by zero in damon_merge_two_regions(). Note that some of the consequences including the WARN_ONCE() and the divide by zero depend on commits that were introduced after the root cause commit 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting"). Fix the problems by checking the assumption and returning an error if the input ranges don't meet the assumption. The issue was discovered [1] by Sashiko. Link: https://lore.kernel.org/20260703165610.92894-1-sj@kernel.org Link: https://lore.kernel.org/20260630041806.151124-1-sj@kernel.org [1] Fixes: 97d482f4592f ("mm/damon/sysfs: reuse damon_set_regions() for regions setting") Signed-off-by: SJ Park Cc: # 5.19.x Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/damon/core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -240,12 +240,19 @@ int damon_set_regions(struct damon_targe { struct damon_region *r, *next; unsigned int i; + unsigned long last_end; int err; for (i = 0; i < nr_ranges; i++) { - if (ALIGN_DOWN(ranges[i].start, min_region_sz) >= - ALIGN(ranges[i].end, min_region_sz)) + unsigned long start, end; + + start = ALIGN_DOWN(ranges[i].start, min_region_sz); + end = ALIGN(ranges[i].end, min_region_sz); + if (start >= end) + return -EINVAL; + if (i > 0 && last_end > start) return -EINVAL; + last_end = end; } /* Remove regions which are not in the new ranges */