Re: [PATCH] tracing: fix incorrect tracer freeing when opening tracing pipe

[Steven Rostedt]

On Sat, 16 Feb 2019 19:19:03 +0800
"zhangyi (F)" <yi.zhang@xxxxxxxxxx> wrote:

> On 2019/2/13 21:36, Steven Rostedt Wrote:
> > On Wed, 13 Feb 2019 20:29:06 +0800
> > "zhangyi (F)" <yi.zhang@xxxxxxxxxx> wrote:
> >   
> >> Commit d716ff71dd12 ("tracing: Remove taking of trace_types_lock in
> >> pipe files") use the current tracer instead of the copy in
> >> tracing_open_pipe(), but it forget to remove the freeing sentence in
> >> the error path.
> >>
> >> Fixes: d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files")  
> > 
> > Thanks.
> > 
> > As this is harmless (frees to NULL is ok, and iter is allocated with
> > kzalloc()), I'm going to just add this for the next merge window.
> >   
> 
> This patch patch want to remove kfree(iter->trace) instead of kfree(iter),
> which is set by tr->current_trace and probably not allocated dynamically.
> So if we kfree such tracer in the error path, it will lead to BUG_ON.
> 

This should have been mentioned in the change log. Anyway, I tagged it
for stable, but it will be pulled in during the next merge window, as
that shouldn't be too long from now.

-- Steve