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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 386B9C433E2 for ; Fri, 11 Sep 2020 11:58:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFE5122206 for ; Fri, 11 Sep 2020 11:58:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599825512; bh=o9cW/liLO9LiEgJpuDhrXaYdblbkJJYZhvq0jGAF6AU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JLaNrjp6diIJTh17T0qXqbyQCuLza5wPaj5ot7VyGV1OKXOHR5SbkR5H38AO37Q78 bCi5MI8JVTobtZapJuFVgm8wqFYt6xwukC0pDBvIHopSYJ7nIQAD0Y23V8b2qdzOwa fXHtW1uxQz3/NPixXuQRXlxZDUgK3U4FaudkOyeU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725768AbgIKL6U (ORCPT ); Fri, 11 Sep 2020 07:58:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:35596 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725710AbgIKL6L (ORCPT ); Fri, 11 Sep 2020 07:58:11 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2B5B3221EB; Fri, 11 Sep 2020 11:58:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599825490; bh=o9cW/liLO9LiEgJpuDhrXaYdblbkJJYZhvq0jGAF6AU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Kq6gJBba1Hy+SzRy3ssBaQfXoE3PFA66PcRd7lYj4u8wdZj18gEXRz713cQZroGyT 4eG2FSlV9yKN2bVvxPA98WTKcri4vs2pFWN952guAhHPMHjoUGxUuvnQTKhSEbqQHu s0MSLmTl+MaXLJlDrIog0mYpmD/RUiVw8YNfAakM= Date: Fri, 11 Sep 2020 13:58:16 +0200 From: Greg Kroah-Hartman To: Salvatore Bonaccorso Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Bob Peterson , Andreas Gruenbacher , Sasha Levin , Daniel.Craig@csiro.au, Nicolas Courtel Subject: Re: [PATCH 4.19 142/206] gfs2: fix use-after-free on transaction ail lists Message-ID: <20200911115816.GB3717176@kroah.com> References: <20200623195316.864547658@linuxfoundation.org> <20200623195323.968867013@linuxfoundation.org> <20200910194319.GA131386@eldamar.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200910194319.GA131386@eldamar.local> Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Sep 10, 2020 at 09:43:19PM +0200, Salvatore Bonaccorso wrote: > Hi, > > On Tue, Jun 23, 2020 at 09:57:50PM +0200, Greg Kroah-Hartman wrote: > > From: Bob Peterson > > > > [ Upstream commit 83d060ca8d90fa1e3feac227f995c013100862d3 ] > > > > Before this patch, transactions could be merged into the system > > transaction by function gfs2_merge_trans(), but the transaction ail > > lists were never merged. Because the ail flushing mechanism can run > > separately, bd elements can be attached to the transaction's buffer > > list during the transaction (trans_add_meta, etc) but quickly moved > > to its ail lists. Later, in function gfs2_trans_end, the transaction > > can be freed (by gfs2_trans_end) while it still has bd elements > > queued to its ail lists, which can cause it to either lose track of > > the bd elements altogether (memory leak) or worse, reference the bd > > elements after the parent transaction has been freed. > > > > Although I've not seen any serious consequences, the problem becomes > > apparent with the previous patch's addition of: > > > > gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list)); > > > > to function gfs2_trans_free(). > > > > This patch adds logic into gfs2_merge_trans() to move the merged > > transaction's ail lists to the sdp transaction. This prevents the > > use-after-free. To do this properly, we need to hold the ail lock, > > so we pass sdp into the function instead of the transaction itself. > > > > Signed-off-by: Bob Peterson > > Signed-off-by: Andreas Gruenbacher > > Signed-off-by: Sasha Levin > > --- > > fs/gfs2/log.c | 11 +++++++++-- > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c > > index d3f0612e33471..06752db213d21 100644 > > --- a/fs/gfs2/log.c > > +++ b/fs/gfs2/log.c > > @@ -877,8 +877,10 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags) > > * @new: New transaction to be merged > > */ > > > > -static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *new) > > +static void gfs2_merge_trans(struct gfs2_sbd *sdp, struct gfs2_trans *new) > > { > > + struct gfs2_trans *old = sdp->sd_log_tr; > > + > > WARN_ON_ONCE(!test_bit(TR_ATTACHED, &old->tr_flags)); > > > > old->tr_num_buf_new += new->tr_num_buf_new; > > @@ -890,6 +892,11 @@ static void gfs2_merge_trans(struct gfs2_trans *old, struct gfs2_trans *new) > > > > list_splice_tail_init(&new->tr_databuf, &old->tr_databuf); > > list_splice_tail_init(&new->tr_buf, &old->tr_buf); > > + > > + spin_lock(&sdp->sd_ail_lock); > > + list_splice_tail_init(&new->tr_ail1_list, &old->tr_ail1_list); > > + list_splice_tail_init(&new->tr_ail2_list, &old->tr_ail2_list); > > + spin_unlock(&sdp->sd_ail_lock); > > } > > > > static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr) > > @@ -901,7 +908,7 @@ static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr) > > gfs2_log_lock(sdp); > > > > if (sdp->sd_log_tr) { > > - gfs2_merge_trans(sdp->sd_log_tr, tr); > > + gfs2_merge_trans(sdp, tr); > > } else if (tr->tr_num_buf_new || tr->tr_num_databuf_new) { > > gfs2_assert_withdraw(sdp, test_bit(TR_ALLOCED, &tr->tr_flags)); > > sdp->sd_log_tr = tr; > > -- > > 2.25.1 > > In Debian two user confirmed issues on writing on a GFS2 partition > with this commit applied. The initial Debian report is at > https://bugs.debian.org/968567 and Daniel Craig reported it into > Bugzilla at https://bugzilla.kernel.org/show_bug.cgi?id=209217 . > > Writing to a gfs2 filesystem fails and results in a soft lookup of the > machine for kernels with that commit applied. I cannot reporduce the > issue myself due not having a respective setup available, but Daniel > described a minimal serieos of steps to reproduce the issue. > > This might affect as well other stable series where this commit was > applied, as there was a similar report for someone running 5.4.58 in > https://www.redhat.com/archives/linux-cluster/2020-August/msg00000.html Can you report this to the gfs2 developers? thanks, greg k-h