linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Benjamin Block <bblock@linux.ibm.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org,
	"James E . J . Bottomley" <jejb@linux.ibm.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org, "Ewan D . Milne" <emilne@redhat.com>,
	Bart Van Assche <bvanassche@acm.org>,
	Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>,
	Mike Snitzer <snitzer@redhat.com>,
	dm-devel@redhat.com, stable@vger.kernel.org
Subject: Re: [PATCH V2 0/2] block/scsi/dm-rq: fix leak of request private data in dm-mpath
Date: Fri, 26 Jul 2019 18:20:46 +0200	[thread overview]
Message-ID: <20190726162046.GA7523@t480-pf1aa2c2> (raw)
In-Reply-To: <20190720030637.14447-1-ming.lei@redhat.com>

Hey Ming Lei,

On Sat, Jul 20, 2019 at 11:06:35AM +0800, Ming Lei wrote:
> Hi,
> 
> When one request is dispatched to LLD via dm-rq, if the result is
> BLK_STS_*RESOURCE, dm-rq will free the request. However, LLD may allocate
> private data for this request, so this way will cause memory leak.

I am confused about this. Probably because I am not up-to-date with
all of blk-mq. But if you free the LLD private data before the request
is finished, what is the LLD doing if the request finishes afterwards?
Would that not be an automatic use-after-free?

> 
> Add .cleanup_rq() callback and implement it in SCSI for fixing the issue,
> since SCSI is the only driver which allocates private requst data in
> .queue_rq() path.
> 
> Another use case of this callback is to free the request and re-submit
> bios during cpu hotplug when the hctx is dead, see the following link:
> 
> https://lore.kernel.org/linux-block/f122e8f2-5ede-2d83-9ca0-bc713ce66d01@huawei.com/T/#t
> 
> V2:
> 	- run .cleanup_rq() in blk_mq_free_request(), as suggested by Mike 

-- 
With Best Regards, Benjamin Block      /      Linux on IBM Z Kernel Development
IBM Systems & Technology Group   /  IBM Deutschland Research & Development GmbH
Vorsitz. AufsR.: Matthias Hartmann       /      Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294


  parent reply	other threads:[~2019-07-26 16:20 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-20  3:06 [PATCH V2 0/2] block/scsi/dm-rq: fix leak of request private data in dm-mpath Ming Lei
2019-07-20  3:06 ` [PATCH V2 1/2] blk-mq: add callback of .cleanup_rq Ming Lei
2019-07-22 16:51   ` Bart Van Assche
2019-07-23  1:00     ` Ming Lei
2019-07-20  3:06 ` [PATCH V2 2/2] scsi: implement .cleanup_rq callback Ming Lei
2019-07-22 15:40   ` Bart Van Assche
2019-07-23  1:03     ` Ming Lei
     [not found]   ` <20190725104629.GC3640@shao2-debian>
2019-07-27  2:15     ` [scsi] ae86a1c553: BUG:kernel_NULL_pointer_dereference,address Ming Lei
2019-07-26 16:20 ` Benjamin Block [this message]
2019-07-27  2:12   ` [PATCH V2 0/2] block/scsi/dm-rq: fix leak of request private data in dm-mpath Ming Lei

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190726162046.GA7523@t480-pf1aa2c2 \
    --to=bblock@linux.ibm.com \
    --cc=axboe@kernel.dk \
    --cc=bvanassche@acm.org \
    --cc=dm-devel@redhat.com \
    --cc=emilne@redhat.com \
    --cc=hare@suse.com \
    --cc=hch@lst.de \
    --cc=jejb@linux.ibm.com \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-scsi@vger.kernel.org \
    --cc=martin.petersen@oracle.com \
    --cc=ming.lei@redhat.com \
    --cc=snitzer@redhat.com \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).