From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from va-2-28.ptr.blmpb.com (va-2-28.ptr.blmpb.com [209.127.231.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 59A0C244685 for ; Tue, 31 Mar 2026 01:56:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.127.231.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774922196; cv=none; b=LvJkRk+iHs7vxcSZkuX/xw8BqLcA5Sdktrl+5//HaCG/56nOj1Uiy7krh6na7iCmuW+HG35UmJpB2jVSMb+4mwIOV7hAWq4rHTZpkaMLJBekxFTDUBbRuCUyHvyj4nerM56mVFzKYcKj4aKncbhqORxpKuXdnSPWwNSgOG8Kmn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774922196; c=relaxed/simple; bh=0UP3yGlxi/4r95qkiwnW++Ud/xrF8OdwRLApZCt02tc=; h=Content-Type:Content-Disposition:Mime-Version:From:References:To: Cc:Date:Message-Id:In-Reply-To:Subject; b=tXWpAFSRJ9y3giNJKTNdFRc/wQyu/BWoBB6uJEm11+TdxP0W982Sw1H92d+LcEVL5VXSBMoKA+YPzQXbq7LJZoNN2MwQQ3GQtyt+KZfqcbmgHX/XA1e1vkPYfiiYdZ+FIwwJM2oOOJz5BecWaqFRsHPJZQXNCjT+4X4K97ofHfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com; spf=none smtp.mailfrom=fnnas.com; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b=MTJqSp5g; arc=none smtp.client-ip=209.127.231.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fnnas.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=fnnas.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=fnnas-com.20200927.dkim.feishu.cn header.i=@fnnas-com.20200927.dkim.feishu.cn header.b="MTJqSp5g" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=s1; d=fnnas-com.20200927.dkim.feishu.cn; t=1774922182; h=from:subject:mime-version:from:date:message-id:subject:to:cc: reply-to:content-type:mime-version:in-reply-to:message-id; bh=8I9QInqfetuFmmtGqZwTyzOOrTim5WzG16S9wMZfaDk=; b=MTJqSp5gFrTQ2srjqSR4kQgw3ZD5xHmnTCB/irVqNpoBQf2fVrKnASjai+yshEHBdni10L 48IOdP5XyJmxpYEsm9Tu5Rx6GA602kphdtnZfCsLClRNkucEy8kxrXcRT/VwU/AdH2dm52 aNICJaiXM2fpo+gMDGEAjAQuIn3e+LfiYKxu7sgTMN4PrKCIiQNvkPiRHl/ymCRvMf6H+v Z0v6kOIoeLP10kzKrjo6Z1zOuRGxAai1BDcvR7pUtjB+EgX1TUYxQrkKwKhRwQ71NS/I3a ELbXtXurJwm9AvlTzgy7lAK7Xa8H3yZ6ZYLo0++L4VmDVPuuE+5AgAv/OeMAOQ== Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Content-Transfer-Encoding: 7bit Precedence: bulk X-Mailing-List: linux-bcache@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 From: "Coly Li" References: <20260330131153.69705-1-mingzhe.zou@easystack.cn> Received: from studio.local ([120.245.64.217]) by smtp.feishu.cn with ESMTPS; Tue, 31 Mar 2026 09:56:19 +0800 To: , Cc: , , , Date: Tue, 31 Mar 2026 09:56:18 +0800 Message-Id: In-Reply-To: <20260330131153.69705-1-mingzhe.zou@easystack.cn> X-Lms-Return-Path: X-Original-From: Coly Li Subject: Re: [PATCH v3] bcache: fix cached_dev.sb_bio use-after-free and crash On Mon, Mar 30, 2026 at 09:11:53PM +0800, mingzhe.zou@easystack.cn wrote: > From: Mingzhe Zou > > In our production environment, we have received multiple crash reports > regarding libceph, which have caught our attention: > > ``` > [6888366.280350] Call Trace: > [6888366.280452] blk_update_request+0x14e/0x370 > [6888366.280561] blk_mq_end_request+0x1a/0x130 > [6888366.280671] rbd_img_handle_request+0x1a0/0x1b0 [rbd] > [6888366.280792] rbd_obj_handle_request+0x32/0x40 [rbd] > [6888366.280903] __complete_request+0x22/0x70 [libceph] > [6888366.281032] osd_dispatch+0x15e/0xb40 [libceph] > [6888366.281164] ? inet_recvmsg+0x5b/0xd0 > [6888366.281272] ? ceph_tcp_recvmsg+0x6f/0xa0 [libceph] > [6888366.281405] ceph_con_process_message+0x79/0x140 [libceph] > [6888366.281534] ceph_con_v1_try_read+0x5d7/0xf30 [libceph] > [6888366.281661] ceph_con_workfn+0x329/0x680 [libceph] > ``` > > After analyzing the coredump file, we found that the address of dc->sb_bio > has been freed. We know that cached_dev is only freed when it is stopped. > > Since sb_bio is a part of struct cached_dev, rather than an alloc every time. > If the device is stopped while writing to the superblock, the released address > will be accessed at endio. > > This patch hopes to wait for sb_write to complete in cached_dev_free. > > Signed-off-by: Mingzhe Zou > Hi Mingzhe, Yeah, this patch is in better shape. Thank for the fix up again. > --- > v2: fix the crash caused by not calling closure_init in v1 > v3: pair the down and up of semaphore sb_write_mutex > --- > drivers/md/bcache/super.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index 64bb38c95895..97d9adb0bf96 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -1373,6 +1373,14 @@ static CLOSURE_CALLBACK(cached_dev_free) > > mutex_unlock(&bch_register_lock); > > + /* > + * Wait for any pending sb_write to complete before free. > + * The sb_bio is embedded in struct cached_dev, so we must > + * ensure no I/O is in progress. > + */ > + down(&dc->sb_write_mutex); > + up(&dc->sb_write_mutex); > + > if (dc->sb_disk) > folio_put(virt_to_folio(dc->sb_disk)); > The patch itself is good. But the previous one (based on closre_sync()) is in Jens block-tree. Let me ask. Hi Jens, Should Mingzhe send a incremental patch based on commit b36478a1fece in block-7.0 branch of linux-block tree? Or Just use this patch to replace the in-linux-block-tree one? Thanks in advance for your hint. Coly Li