lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 12 Dec 2016 11:49:20 -0500 From: Steven Rostedt <rostedt@...dmis.org> To: Namhyung Kim <namhyung@...nel.org> Cc: "Cc: LKML" <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, stable <stable@...r.kernel.org>, Namhyung Kim <namhyung.kim@....com> Subject: Re: [for-next][PATCH 7/8] fgraph: Handle a case where a tracer ignores set_graph_notrace On Tue, 13 Dec 2016 01:30:01 +0900 Namhyung Kim <namhyung@...nel.org> wrote: > Sorry to miss updating those tracers. I guess it's no more necessary once > the patch 8 is applied so that functions in the notrace filter will not be > recorded. > > Or maybe we need to change the prepare_ftrace_return() so that the > graph_entry callback should be called after ftrace_push_return_trace() as > some archs do. I plan on updating fgraph in general so this should all be handled then. > > > > > Have the print functions handle cases where a tracer still records functions > > even when they are in set_graph_notrace. > > I think it'd be better (or consistent, at least) not printing negative index > records rather than showing entry only. I thought about this too, but I'm more concerned about it not crashing the kernel than to show a proper trace. The fix will just make sure it doesn't crash. > > > > > Also add warnings if the depth is below zero before accessing the array. > > > > Note, the function graph logic will still prevent the return of these > > functions from being recorded, which means that they will be left hanging > > without a return. For example: > > > > # echo '*spin*' > set_graph_notrace > > # echo 1 > options/display-graph > > # echo wakeup > current_tracer > > # cat trace > > [...] > > _raw_spin_lock() { > > preempt_count_add() { > > do_raw_spin_lock() { > > update_rq_clock(); > > > > Where it should look like: > > > > _raw_spin_lock() { > > preempt_count_add(); > > do_raw_spin_lock(); > > } > > update_rq_clock(); > > If set_graph_notrace works correctly, it should be just: > > update_rq_clock(); Which is what it should look like after patch 8. But I didn't mark 8 as stable as that's more of a feature. As wakeup and irqsoff doesn't use notrace yet. Yeah, notrace may break it a bit, but since this is the first someone noticed it, I don't think it's used much. I wanted the simplest fix for stable. -- Steve
Powered by blists - more mailing lists