From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D4AE710987A5 for ; Fri, 20 Mar 2026 16:36:16 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4207F6B0122; Fri, 20 Mar 2026 12:36:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3AAB86B0123; Fri, 20 Mar 2026 12:36:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2C05A6B0124; Fri, 20 Mar 2026 12:36:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 1A25B6B0122 for ; Fri, 20 Mar 2026 12:36:16 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id C090D1602BC for ; Fri, 20 Mar 2026 16:36:15 +0000 (UTC) X-FDA: 84566993910.19.A1A67B4 Received: from sender-of-o57.zoho.eu (sender-of-o57.zoho.eu [136.143.169.57]) by imf01.hostedemail.com (Postfix) with ESMTP id EE7CC40005 for ; Fri, 20 Mar 2026 16:36:13 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=objecting.org header.s=zmail header.b=I+rSrwmd; spf=pass (imf01.hostedemail.com: domain of objecting@objecting.org designates 136.143.169.57 as permitted sender) smtp.mailfrom=objecting@objecting.org; dmarc=pass (policy=quarantine) header.from=objecting.org; arc=pass ("zohomail.eu:s=zohoarc:i=1") ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774024574; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=xBhz+FP718xfFTo+Jqt21ir9B4N+Sz9WG+S91iYYSqU=; b=bDe7EtSXFQKhjHqKj0eL19xvKKz2j/8BHGchOJUQDrS01klQz1AcPaNFmUG8xFhc/ILnJs FsUbDFpqqaXZpATIDwh49Xdg9X5KTvza4N4WIzDpp9NPYwSqb9ntIq5f2ZI05gemKR8pfp A+j7ZjU9ou3kOVmyQevapiPwXK9w3kU= ARC-Authentication-Results: i=2; imf01.hostedemail.com; dkim=pass header.d=objecting.org header.s=zmail header.b=I+rSrwmd; spf=pass (imf01.hostedemail.com: domain of objecting@objecting.org designates 136.143.169.57 as permitted sender) smtp.mailfrom=objecting@objecting.org; dmarc=pass (policy=quarantine) header.from=objecting.org; arc=pass ("zohomail.eu:s=zohoarc:i=1") ARC-Seal: i=2; s=arc-20220608; d=hostedemail.com; t=1774024574; a=rsa-sha256; cv=pass; b=sUyP8XQKJSGS+R4fyZUN97/MyjkDgq4pKOwWKyO4HnnzqEM6GZHIpkYajrU/gOIasPlvKZ zrUXM1BBn0/56I6kZwAPrOQrNZd2uTJmug2fnwlA8EWZ3SivtkHMj/qEb2Re2bYCwYPxvX 9FhG7DR2sQn+fOUEytZj1mmRpQSIYM0= ARC-Seal: i=1; a=rsa-sha256; t=1774024563; cv=none; d=zohomail.eu; s=zohoarc; b=ff8X3tljHjklyFzeIFOMCAdNbLmebNvpYED9ZqvO5oAD7NDG1a45ss15UN6rHaeUpEF87bR6hsw4wmrIsW2j4KmhzuOc7YqAQmp49YiORUQdPIhzYlGKnYBxHdBY6IvtkY15H0jjAhxHRjbrnZfAMb0ojGsK1vvlG2ydZXgLss0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.eu; s=zohoarc; t=1774024563; 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=xBhz+FP718xfFTo+Jqt21ir9B4N+Sz9WG+S91iYYSqU=; b=Et+EfbnAdIfTOdfn2PjpJQeP4ypoP4uxvfKy9C1+AVGQSrKOzpFxuK7BPala0qvsStG2h0MF5C9Vz0ZZBbUMHrev2ZelqjEqefje9uXmFIr7pMwMhYnilH65aFwi3j1ZEFivFfdGiaZRrG4H54WJnbRnJm0P6hbq1y5HQZiyQUg= 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=1774024563; 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=xBhz+FP718xfFTo+Jqt21ir9B4N+Sz9WG+S91iYYSqU=; b=I+rSrwmdO5diJIt0LdFNl3Yk3dlXhjTt0x0zyF30VEYe6opl27xXPDSUJJ3tXuYj 1CMYjf3lBkYeKUDR3YP7NTyVHGex8JG3e8me/ea7fJzJV7H4XsLbLeKHaO5n+mTseGj 7/xRFtAU2A4eivvzCxi6s6B3sCWpX/vEWTlm4eh0= Received: by mx.zoho.eu with SMTPS id 1774024562167191.42267947695075; 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 2/3] mm/damon/sysfs: check contexts->nr before accessing contexts_arr[0] Date: Fri, 20 Mar 2026 16:35:58 +0000 Message-Id: <20260320163559.178101-2-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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External X-Rspamd-Queue-Id: EE7CC40005 X-Stat-Signature: bry4nymuogncypksz1dye64wm1ryh1nz X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1774024573-362637 X-HE-Meta: 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 EWCRfdiJ u9bngaVE2UcgTEb2X+HUZjSZIQQwsY8oY9amNJVzoPeaO1f8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Multiple sysfs command paths dereference contexts_arr[0] without first verifying that nr_contexts >= 1. A user can set nr_contexts to 0 via sysfs while DAMON is running, causing NULL pointer dereferences. Guard all commands (except OFF) at the entry point of damon_sysfs_handle_cmd(). Fixes: 0ac32b8affb5 ("mm/damon/sysfs: support DAMOS stats") Cc: # 5.18.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 b573b9d60784..ddc30586c0e6 100644 --- a/mm/damon/sysfs.c +++ b/mm/damon/sysfs.c @@ -1749,6 +1749,9 @@ static int damon_sysfs_update_schemes_tried_regions( static int damon_sysfs_handle_cmd(enum damon_sysfs_cmd cmd, struct damon_sysfs_kdamond *kdamond) { + if (cmd != DAMON_SYSFS_CMD_OFF && kdamond->contexts->nr != 1) + return -EINVAL; + switch (cmd) { case DAMON_SYSFS_CMD_ON: return damon_sysfs_turn_damon_on(kdamond); -- 2.34.1