From nobody Mon Sep 28 13:59:37 2026 Received: from oss.cyber.gouv.fr (oss.cyber.gouv.fr [51.159.188.251]) (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 6FC3B33CE86; Thu, 20 Aug 2026 21:08:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.159.188.251 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787260090; cv=none; b=dWYuKOo1tZunTkhDyueMCdyXjz+HkaSdapzuFbuk6xz4jQPqpAcdjb4oj4SNQaDnAjuMsbwrqXK85SXXU2qFZIYDFwPgebJgUGL8ZVgg0isP6eQaViB2CMXT3GCXYBblyn+jBoKockgTEclRQRYW8Cx+v3lwZmSMAvVOXyy1DPU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787260090; c=relaxed/simple; bh=YjymKqafH5iq1pxMG50aj9Ce0z3orJEy33n15quSfAM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=XSzhlEPxmwHqBbY7kFDFKOPcfBxJ6LO5a6j9qU1WYy0+Q7cblqQ5774zmfNHNalSjdM4+a9VOt+PckJUh43W7MYfTMDXX5nsXLnGGkl3tlh0JqYuNNtODI32Yr8CpwDTE/oDhBQyoT05KcNbGcCRiE9h0PJEryYLfGzWeTfgkyw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oss.cyber.gouv.fr; spf=pass smtp.mailfrom=oss.cyber.gouv.fr; dkim=pass (2048-bit key) header.d=oss.cyber.gouv.fr header.i=@oss.cyber.gouv.fr header.b=QFkUPk53; arc=none smtp.client-ip=51.159.188.251 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oss.cyber.gouv.fr header.i=@oss.cyber.gouv.fr header.b="QFkUPk53" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=oss.cyber.gouv.fr; s=default; h=Content-Transfer-Encoding:Content-Type: MIME-Version:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=3MrXK8duEoEc25OZXQJo70Rz1o/CTExuLYZC06YeBQM=; b=QFkUPk531zZDcd4jLKb/8HA8HU /mZvt8z9kxYmMwcAlaVDO1WcGmXA7weJaFcesdsC11jE04WuKxz88idxlHhqT9rmjx9V4I/U2/JgW CmhF7tTfX1ijatk7tnpGI6w0Ep89jINM0/QX3ziy5SLYIUPwypaxe4L/yIyRVs9xyF6dnuuoAvCGk 3xn+oLkiSZV9fmBgYykUQ5tBp4U3jzYu2eDQoyAvV/A5xmhWeHO6Za7FRheMBjiP3kWvRiLmxODCR iQjj6bGq1Jv9cHtbuGUecAjuOzz0zzD3VmdQtPTPo8835oBMARrEGiZ26k4YrGYlf4LPZx2Jk9Xlk MuaU+yLA==; Received: from [151.115.150.205] (port=38124 helo=gepetto..) by pf-012.whm.fr-par.scw.cloud with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.99.5) (envelope-from ) id 1wx9zZ-00000009ZWc-3hX1; Thu, 20 Aug 2026 23:08:05 +0200 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= To: song@kernel.org, yukuai@fygo.io Cc: magiclinan@didiglobal.com, xiao@kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= Subject: [PATCH] md: reject v0.90 arrays with too many devices Date: Thu, 20 Aug 2026 21:07:03 +0000 Message-ID: <20260820210703.3035608-2-Jeremy.Jean@oss.cyber.gouv.fr> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - pf-012.whm.fr-par.scw.cloud X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - oss.cyber.gouv.fr X-Get-Message-Sender-Via: pf-012.whm.fr-par.scw.cloud: authenticated_id: jeremy.jean@oss.cyber.gouv.fr X-Authenticated-Sender: pf-012.whm.fr-par.scw.cloud: jeremy.jean@oss.cyber.gouv.fr X-Source: X-Source-Args: X-Source-Dir: The v0.90 superblock has room for MD_SB_DISKS device descriptors, but super_90_load() only rejects nonpositive raid_disks values. A crafted superblock can therefore copy a larger value into mddev->raid_disks. When metadata is next updated, super_90_sync() walks sb->disks[] up to that count and reads and writes beyond the 4 KiB superblock buffer. A checksum-valid RAID1 member advertising 64 devices can be assembled by mdadm --incremental --run. The first write to the array then produces out-of-bounds writes from super_90_sync() under KASAN. Reject device counts that cannot be represented by the v0.90 format while loading the superblock. Assisted-by: Codex:gpt-5 Signed-off-by: J=C3=A9r=C3=A9my Jean --- drivers/md/md.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index d1465bcd86c8..873a0e5fce7d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -1398,7 +1398,7 @@ static int super_90_load(struct md_rdev *rdev, struct= md_rdev *refdev, int minor goto abort; } =20 - if (sb->raid_disks <=3D 0) + if (sb->raid_disks <=3D 0 || sb->raid_disks > MD_SB_DISKS) goto abort; =20 if (md_csum_fold(calc_sb_csum(sb)) !=3D md_csum_fold(sb->sb_csum)) { --=20 2.47.3