Re: [PATCH] blktrace: Fix uaf in blk_trace access after removing by sysfs

[Zhihao Cheng]

在 2021/9/22 13:21, Christoph Hellwig 写道:
Hi Christoph,
> On Fri, Sep 10, 2021 at 05:21:20PM +0800, Zhihao Cheng wrote:
> > +		else {
> > +			/*
> > +			 * Don't remove blk_trace under running state, in
> > +			 * case triggering use-after-free in function
> > +			 * __blk_add_trace().
> > +			 */
> > +			if (bt->trace_state != Blktrace_running)
> > +				ret = blk_trace_remove_queue(q);
> > +			else
> > +				ret = -EBUSY;
> > +		}
> >   		goto out_unlock_bdev;
> So who is going to eventually call blk_trace_free in this case?
Agree. How about removing blk_trace from running_list and stopping it 
before calling blk_trace_free()?
> Also Having the check in blk_trace_remove_queue would seem a little
> cleaner.
Oh right, will move the check in v2.