From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender-of-o57.zoho.eu (sender-of-o57.zoho.eu [136.143.169.57]) (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 A0D46378823; Fri, 20 Mar 2026 16:36:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.169.57 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774024580; cv=pass; b=qKw3JDOwyv8MpIbS2Q28DzvezEqy+PH0XLy5fFZDzKWp5+qe4SGsbKUhvvpW8h6mn9g20DrFupENhrH9TawWhTgTLoP+E5BS70q1zqBCc9haIdL31Am62VP2dm6+iCnOENsJYR9aEEb7s25mROMlVPS4ISin0fInwi4yOuJXvR0= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774024580; c=relaxed/simple; bh=cgiBTMTJREfr9NZlbEJek9bHXIpKX6CcaXj/YeMtBG8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=n6gGu6OZZcFb9almpfBPiq2hypkp5F6y/EWty+fGki/P2nx9AC+8oZL2aVDHVzF71N5nA2dPko7ql2E0ivRiZ1KhPQk5so5PfyZq1REmPa8idTPUbWotpZsVxVFrJdg//VyjjCZSWrVql2jmnGsk4BYUoSWa0ILxIw46E9SH1/o= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=objecting.org; spf=pass smtp.mailfrom=objecting.org; dkim=pass (1024-bit key) header.d=objecting.org header.i=objecting@objecting.org header.b=XWOS+2BX; arc=pass smtp.client-ip=136.143.169.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=objecting.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=objecting.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=objecting.org header.i=objecting@objecting.org header.b="XWOS+2BX" ARC-Seal: i=1; a=rsa-sha256; t=1774024565; cv=none; d=zohomail.eu; s=zohoarc; b=fbWEpYSnPQTKtwmxLGF8DiucdelmuuJUj9/4VuCbp+XgAewF4l+1KCKx8Fkzv67o8Ls8PTpkl+9z2CAXKZGm1TAoYBA3N8M8wHT+0RZUcXZR057gnHceIDQPGFL9qVdsja79K47phyi4xWEzAn5d5oxH41liILMxCkpScjDqh3Q= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.eu; s=zohoarc; t=1774024565; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=ZOAuFTk2fYZ7Opzh+m6bCHOI9jrLB+RqVBg8xOebPgo=; b=Q2yYD6NbDrV08oAoO5q/ZU7Dfusf9m7lEJVhMZZ1xji9eC29XTJjQJfMAGaGEWcpeO5khPUxAsvSUnBZ+S/L2LcTip3c1W/DVmhGcOOqOMucd6suqFkr5fHOzsp6S2jy2YfSXwq9lfitGHNvNcD0NjUeyje/fFA389pukhH0pCI= ARC-Authentication-Results: i=1; mx.zohomail.eu; dkim=pass header.i=objecting.org; spf=pass smtp.mailfrom=objecting@objecting.org; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1774024565; s=zmail; d=objecting.org; i=objecting@objecting.org; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-Id:Message-Id:In-Reply-To:References:MIME-Version:Content-Transfer-Encoding:Reply-To; bh=ZOAuFTk2fYZ7Opzh+m6bCHOI9jrLB+RqVBg8xOebPgo=; b=XWOS+2BXKdlYAbPn9t42aq7nKVQnYSzg/WNvGmRcVR50uBMfSETecgYHhS0XdSN6 80u4Ki2v/rnDLWAfENyt73PNk+yOi41535uTwU78G+HpMfkZ7SPF0B6MzofZu3DGI/S Ur2DmBgXu9eWcivL358u1yZOF621JYGDkormrTOo= Received: by mx.zoho.eu with SMTPS id 1774024562740540.8427781838304; Fri, 20 Mar 2026 17:36:02 +0100 (CET) From: Josh Law To: SeongJae Park , Andrew Morton Cc: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Josh Law , stable@vger.kernel.org Subject: [PATCH v2 3/3] mm/damon/sysfs: check contexts->nr in repeat_call_fn Date: Fri, 20 Mar 2026 16:35:59 +0000 Message-Id: <20260320163559.178101-3-objecting@objecting.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260320163559.178101-1-objecting@objecting.org> References: <20260320163559.178101-1-objecting@objecting.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(), damon_sysfs_upd_schemes_stats(), and damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. If nr_contexts is set to 0 via sysfs while DAMON is running, these functions dereference contexts_arr[0] and cause a NULL pointer dereference. Add the missing check. Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work") Cc: # 6.17.x Signed-off-by: Josh Law Reviewed-by: SeongJae Park --- mm/damon/sysfs.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c index ddc30586c0e6..6a44a2f3d8fc 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1620,9 +1620,12 @@ static int damon_sysfs_repeat_call_fn(void *data) if (!mutex_trylock(&damon_sysfs_lock)) return 0; + if (sysfs_kdamond->contexts->nr != 1) + goto out; damon_sysfs_upd_tuned_intervals(sysfs_kdamond); damon_sysfs_upd_schemes_stats(sysfs_kdamond); damon_sysfs_upd_schemes_effective_quotas(sysfs_kdamond); +out: mutex_unlock(&damon_sysfs_lock); return 0; } -- 2.34.1