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 736B136C588; Sun, 13 Sep 2026 17:17:15 +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=1789319836; cv=none; b=IEsYdiAf9HFUjhcYe+xApVBZ2wsDz0WXI1qnCJYGRuSfX568Kp3YeL6Dx/njmQJXQMQCL+jl72rNZFD3MFliXySvfUxht1V9fHPWrjBNYC20SMGwd1kMFM0+9iTLLXa+hsdrNLlzVGLZwQUjrURWtDdTEGXxkVanM2Y+FbdsMh8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789319836; c=relaxed/simple; bh=gZK1bNR/6VsrE2g3Gf0chVwSQZHcPPaYBk/SDLvircU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ul+S7uskQcw/00CXwfTzdGjyKZu1tsnzXZ2Z9JOPuvXaLWWTMPfm5pYkbAus5fIwR8LSeZcxPNjpz2SeUWc6sv0A25ojgcpszoeQrZ3LTBWIPhXrGv+w57B3Ap+Cqw+kIP6PgR+Sje+Vx4KIrX5+rph6bo64aRX4yj8QF6GbKvM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j1k7zoJA; 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="j1k7zoJA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE5881F00898; Sun, 13 Sep 2026 17:17:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789319835; bh=umQcJFGrr068QYat6Lud6jcAzEmAFL/l4IbhvroBRbM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=j1k7zoJAgMukJ87qFcCabtTBQywMrBVQHbaRWC/DyUpvXwM47ftkD1bexp32XZFF7 b/8M3iKWwESa2g4k/bLHORL1gcqtYrbrIuL0R3jcq5K8meV/q3ARaDyHya0v70JCi0 huUzxAOePyQ3EDjdN9OkxU2Zp1uiIWShkEwoyu09GUnDWnhLcTdtzLl3mGDaDIhC6J pprqvoHR9GKtmX5r36JoYzQY8h9pDU1befab3UYj9t8gFTaRHk/FLZoUdIeThDSM65 4RLXgTsEbCZiIaqbWZdkwHSWW/qUSdwHa953t14G+u7XY35F0Iqm7WlghQavn3TZfu BW3yxMAaVyREQ== From: SJ Park To: Cc: SJ Park , stable@vger.kernel.org, Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 1/8] mm/damon/sysfs-schemes: read sysfs_filter->addr_range only once Date: Sun, 13 Sep 2026 10:16:58 -0700 Message-ID: <20260913171706.103052-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260913171706.103052-1-sj@kernel.org> References: <20260913171706.103052-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit DAMON sysfs interface reads the user-provided address range arguments for addr type DAMOS filter twice. Once for validation, and once again for assignments to the variable that will be passed to the core layer. If the user updates the argument in parallel, an invalid address range could be passed to the core layer. Avoid it by doing the assignments first, and then validating the assigned variables before passing those to the core layer. User impact of the bug should be trivial. From the core layer's perspective, the invalid address range is not really invalid. It just works as having a weird address range. No critical issues such as a crash or a leak could happen. And sane users ain't do such parallel arguments update anyway. If they do, such racy behavior is arguably somewhat expected and deserved. That said, there is no reason to keep such races. Fixes: 2f1abcfccd86 ("mm/damon/sysfs-schemes: support address range type DAMOS filter") Cc: # 6.6.x Signed-off-by: SJ Park --- mm/damon/sysfs-schemes.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 3de4d804e049f..3c1c1cb387fec 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -2831,12 +2831,12 @@ static int damon_sysfs_add_scheme_filters(struct damos *scheme, return err; } } else if (filter->type == DAMOS_FILTER_TYPE_ADDR) { - if (sysfs_filter->addr_range.end < - sysfs_filter->addr_range.start) { + filter->addr_range = sysfs_filter->addr_range; + if (filter->addr_range.end < + filter->addr_range.start) { damos_destroy_filter(filter); return -EINVAL; } - filter->addr_range = sysfs_filter->addr_range; } else if (filter->type == DAMOS_FILTER_TYPE_TARGET) { filter->target_idx = sysfs_filter->target_idx; } else if (filter->type == DAMOS_FILTER_TYPE_HUGEPAGE_SIZE) { -- 2.47.3