Messages in this thread | | | Date | Fri, 10 Feb 2017 19:37:53 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC][PATCH] tracing: Have traceprobe_probes_write() not access userspace unnecessarily |
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On Fri, 10 Feb 2017 08:53:02 +0100 Ingo Molnar <mingo@kernel.org> wrote:
> > * Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > On Thu, 9 Feb 2017 18:04:58 -0500 > > Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > > > > The code in traceprobe_probes_write() reads up to 4096 bytes from userpace > > > for each line. If userspace passes in several lines to execute, the code > > > will do a large read for each line, even though, it is highly likely that > > > the first read from userspace received all of the lines at one. > > > > > > I changed the logic to do a single read from userspace, and to only read > > > from userspace again if not all of the read from userspace made it in. > > > > > > I tested this by adding printk()s and writing files that would test -1, ==, > > > and +1 the buffer size, to make sure that there's no overflows and that if a > > > single line is written with +1 the buffer size, that it fails properly. > > > > > > > Thanks Steve! > > > > Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > > > BTW, this can conflict with my previous patch. > > > > https://lkml.org/lkml/2017/2/6/1048 > > https://lkml.org/lkml/2017/2/7/203 > > > > I'll update this. Ingo, Can I send these patch to Steve? > > Sure, I've not applied your patch yet - mind sending it to Steve on top of Steve's > patch?
Of course, yes. :)
Thanks!
> > Thanks, > > Ingo
-- Masami Hiramatsu <mhiramat@kernel.org>
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