From: Ming Lei <ming.lei@redhat.com>
To: Benjamin Block <bblock@linux.ibm.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: Sat, 27 Jul 2019 10:12:20 +0800 [thread overview]
Message-ID: <20190727021219.GA6926@ming.t460p> (raw)
In-Reply-To: <20190726162046.GA7523@t480-pf1aa2c2>
On Fri, Jul 26, 2019 at 06:20:46PM +0200, Benjamin Block wrote:
> 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?
Wrt. this special use case, the underlying request is totally covered by
dm-rq after .queue_rq() returns BLK_STS_*RESOURCE. So the request won't
be re-dispatched by blk-mq at all.
thanks,
Ming
prev parent reply other threads:[~2019-07-27 2:12 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 ` [PATCH V2 0/2] block/scsi/dm-rq: fix leak of request private data in dm-mpath Benjamin Block
2019-07-27 2:12 ` Ming Lei [this message]
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