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[209.132.180.67]) by mx.google.com with ESMTP id t12-v6si2032530pgf.265.2018.08.22.09.10.59; Wed, 22 Aug 2018 09:11:14 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726798AbeHVTeE (ORCPT + 99 others); Wed, 22 Aug 2018 15:34:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:33952 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726550AbeHVTeE (ORCPT ); Wed, 22 Aug 2018 15:34:04 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CA206AF79; Wed, 22 Aug 2018 16:08:32 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 958C71E361C; Wed, 22 Aug 2018 18:08:32 +0200 (CEST) Date: Wed, 22 Aug 2018 18:08:32 +0200 From: Jan Kara To: Jeremy Cline Cc: Jan Kara , linux-kernel@vger.kernel.org, Josh Poimboeuf , stable@vger.kernel.org Subject: Re: [PATCH 2/2] fs/quota: Fix spectre gadget in do_quotactl Message-ID: <20180822160832.GF23037@quack2.suse.cz> References: <20180731013731.1987-1-jcline@redhat.com> <20180731013731.1987-3-jcline@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180731013731.1987-3-jcline@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 31-07-18 01:37:31, Jeremy Cline wrote: > 'type' is user-controlled, so sanitize it after the bounds check to > avoid using it in speculative execution. This covers the following > potential gadgets detected with the help of smatch: > > * fs/ext4/super.c:5741 ext4_quota_read() warn: potential spectre issue > 'sb_dqopt(sb)->files' [r] > * fs/ext4/super.c:5778 ext4_quota_write() warn: potential spectre issue > 'sb_dqopt(sb)->files' [r] > * fs/f2fs/super.c:1552 f2fs_quota_read() warn: potential spectre issue > 'sb_dqopt(sb)->files' [r] > * fs/f2fs/super.c:1608 f2fs_quota_write() warn: potential spectre issue > 'sb_dqopt(sb)->files' [r] > * fs/quota/dquot.c:412 mark_info_dirty() warn: potential spectre issue > 'sb_dqopt(sb)->info' [w] > * fs/quota/dquot.c:933 dqinit_needed() warn: potential spectre issue > 'dquots' [r] > * fs/quota/dquot.c:2112 dquot_commit_info() warn: potential spectre > issue 'dqopt->ops' [r] > * fs/quota/dquot.c:2362 vfs_load_quota_inode() warn: potential spectre > issue 'dqopt->files' [w] (local cap) > * fs/quota/dquot.c:2369 vfs_load_quota_inode() warn: potential spectre > issue 'dqopt->ops' [w] (local cap) > * fs/quota/dquot.c:2370 vfs_load_quota_inode() warn: potential spectre > issue 'dqopt->info' [w] (local cap) > * fs/quota/quota.c:110 quota_getfmt() warn: potential spectre issue > 'sb_dqopt(sb)->info' [r] > * fs/quota/quota_v2.c:84 v2_check_quota_file() warn: potential spectre > issue 'quota_magics' [w] > * fs/quota/quota_v2.c:85 v2_check_quota_file() warn: potential spectre > issue 'quota_versions' [w] > * fs/quota/quota_v2.c:96 v2_read_file_info() warn: potential spectre > issue 'dqopt->info' [r] > * fs/quota/quota_v2.c:172 v2_write_file_info() warn: potential spectre > issue 'dqopt->info' [r] > > Additionally, a quick inspection indicates there are array accesses with > 'type' in quota_on() and quota_off() functions which are also addressed > by this. > > Cc: Josh Poimboeuf > Cc: stable@vger.kernel.org > Signed-off-by: Jeremy Cline OK, this looks good. I'll take both patches through my tree (I'll fixup the first patch myself). Honza > --- > > This patch isn't going to cleanly apply to stable without the "fs/quota: > Replace XQM_MAXQUOTAS usage with MAXQUOTAS" patch, but I'm not sure that > patch is really stable material and XQM_MAXQUOTAS has been 3 since > pre-v4.4 so the end result will be the same even if that patch isn't > backported. > > fs/quota/quota.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/quota/quota.c b/fs/quota/quota.c > index d403392d8a0f..f0cbf58ad4da 100644 > --- a/fs/quota/quota.c > +++ b/fs/quota/quota.c > @@ -18,6 +18,7 @@ > #include > #include > #include > +#include > > static int check_quotactl_permission(struct super_block *sb, int type, int cmd, > qid_t id) > @@ -701,6 +702,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, > > if (type >= MAXQUOTAS) > return -EINVAL; > + type = array_index_nospec(type, MAXQUOTAS); > /* > * Quota not supported on this fs? Check this before s_quota_types > * since they needn't be set if quota is not supported at all. > -- > 2.17.1 > > -- Jan Kara SUSE Labs, CR