From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.127.231.54 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794359837; b=eH6NEPzVq+zStf00Ee8/aoqGEACKaS5hAzex3OmTVKpc+BtGhbkbwHZnmidqAv1/cWO6 l13AHkfHtVHwIjRYTHx8Gib6ESY/PKA0sSgjXedtSF5Ic+tjCD1fyP/xVDFIvgdrToios HJFvw6L2VW+YHYxzR1iVgqFE9YT1vfHN4ayvMal5s48FSPJi/zVOWqFc83GqoV5PKgbi/ GHvb21TajwrmnrGfINXIYfvGO9et8fVIQTF0znxnRCGxGBd6GobZrxN8Y+gO93ZIDhu67 rkBN2wCuNUi+02qOF+wFjrIz2XgxjWPK0zK3URlqT+EUzhCIQl0D9kgR45zjWyEQEVQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794359837; h=DMARC-Filter:DKIM-Signature:To:Cc:From:Mime-Version: X-Lms-Return-Path:X-Original-From:Message-Id:References:Subject: Content-Type:Received:User-Agent:Reply-To:Date: Content-Transfer-Encoding:In-Reply-To; bh=FRQiyK5wJHX+Y1daTLJ2LKb8Axz2eA5lQft1YdiVGfc=; b=puCdQLeDoqUi3FOEmKRkH8KWBwwl+/FNM6mgvCgNxT4/YwDYr11ndWcnTuw1uzP5Sxfl AHZUy0As7poo+gCtsQtJKqqz610jG1VQWscIR+i7Ige7fQHd5G1TZ+TN4PodJHEkhf/gh UOSzuMgGMJhp3E63paUsN0AZJdy8cBSTPwPykXo1XS2dloH3OklCu8AMxvacX+2HqR2uj 2o/3M7MtrrYPvMwWVDz4zDv4mGkbkh6Dl1+0cp3SwJfAjtywHknsbkvrjUIbb32YPrlVm A4xL8gDqDRmMR4/LgCTltcVuc77tqKp0RPm068Kw7PRQnbJypaTA62jHVhV4CC1wXkA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=fygo.io; spf=pass smtp.mailfrom=fygo.io; dkim=pass header.d=fygo-io.20200929.dkim.larksuite.com header.i=@fygo-io.20200929.dkim.larksuite.com header.a=rsa-sha256 header.s=s1 header.b=EefnTuwY; arc=none smtp.remote-ip=209.127.231.54 Received: from va-2-54.ptr.blmpb.com (va-2-54.ptr.blmpb.com [209.127.231.54]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EDAB4606A31C for ; Wed, 11 Nov 2026 01:17:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org EDAB4606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=fygo.io Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fygo.io Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=fygo-io.20200929.dkim.larksuite.com header.i=@fygo-io.20200929.dkim.larksuite.com header.a=rsa-sha256 header.s=s1 header.b=EefnTuwY DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=s1; d=fygo-io.20200929.dkim.larksuite.com; t=1794359826; h=from:subject:mime-version:from:date:message-id:subject:to:cc: reply-to:content-type:mime-version:in-reply-to:message-id; bh=FRQiyK5wJHX+Y1daTLJ2LKb8Axz2eA5lQft1YdiVGfc=; b=EefnTuwY61fLIkSVE3kBqheu+HHRcrnhh+mXYw/F37xDS6ceQJhIq/yusMsayi0yysM+Oa Tc3PudLrjj1a+OT99tVdT3Eu779Est0rOalBmbfvhfJar/0nY1Om+s8njl8e0YEPtt6oae ONZXMii6ictxr6umS2XXWXRzZwq7Pdj/q47omamMs1X9XDDLLwicCr6fWW8/k+yyTswoik nYura3K71hGtWx6MmeGjhmu2DBdlz1GkGi6vNRboDeOEwwmmStJyKudlWHevnKIizcTsiT EylB4bWBBualvUa6jEobALGp/oEInfLuYItmyZkAsAwTXav+jWI5fsXPHgl5+Q== To: "Sajal Gupta" , "Song Liu" , "yu kuai" Cc: "Li Nan" , "Xiao Ni" , , , From: "yu kuai" X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 X-Lms-Return-Path: X-Original-From: yu kuai Message-Id: References: <20261102122430.39209-1-sajal2005gupta@gmail.com> Subject: Re: [PATCH] md: fix use-after-free in md_attr_store() Content-Type: text/plain; charset=UTF-8 Received: from [192.168.1.104] ([39.182.0.55]) by smtp.larksuite.com with ESMTPS; Wed, 11 Nov 2026 01:17:05 +0000 User-Agent: Mozilla Thunderbird Reply-To: yukuai@fygo.io Date: Wed, 11 Nov 2026 09:17:02 +0800 Content-Transfer-Encoding: quoted-printable In-Reply-To: <20261102122430.39209-1-sajal2005gupta@gmail.com> =E5=9C=A8 2026/11/2 20:23, Sajal Gupta =E5=86=99=E9=81=93: > md_attr_store() calls sysfs_break_active_protection() for a "clear" > write to array_state before it calls mddev_get(). > sysfs_break_active_protection() does kobject_get() on the mddev > kobject. If the array is concurrently being deleted, the kobject > refcount can already be zero, which triggers "refcount_t: addition on 0; > use-after-free". > > Fix by calling mddev_get() first. If the array is being deleted it > fails with -EBUSY before the kobject is touched, and if it succeeds the > array cannot be freed until mddev_put(). The -EBUSY path no longer > needs to call sysfs_unbreak_active_protection(). > > Fixes: 9e59d609763f ("md: call del_gendisk in control path") > Reported-by:syzbot+dcad997ed2b5bd95cc5e@syzkaller.appspotmail.com > Closes:https://syzkaller.appspot.com/bug?extid=3Ddcad997ed2b5bd95cc5e > Tested-by:syzbot+dcad997ed2b5bd95cc5e@syzkaller.appspotmail.com > Signed-off-by: Sajal Gupta > --- > drivers/md/md.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) Applied --=20 Thanks, Kuai