linux-kernel - Re: [PATCH 0/6] tracing: Fix removing instances while reading/writing to their files

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Message-ID: <CA+G9fYt1dC7=pggtwX2D3jibbLweg+a2LnvYtxfF1nCnqELZSg@mail.gmail.com>
Date:   Thu, 7 Sep 2023 18:54:46 +0530
From:   Naresh Kamboju <naresh.kamboju@...aro.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zheng Yejian <zhengyejian1@...wei.com>
Subject: Re: [PATCH 0/6] tracing: Fix removing instances while reading/writing
 to their files

On Thu, 7 Sept 2023 at 08:17, Steven Rostedt <rostedt@...dmis.org> wrote:
>
>
> It appears that the dynamic code of eventfs has caused a race window
> to open up a bit more and showed that several files were not protected
> by the trace array ref count. This means that a task could open one
> of the files in an instance, remove the instance, and still be able to
> read or write to that file. That access will then cause a "use-after-free"
> bug.
>
> Close those holes!
>
> Also, fix a left over unused variable in the eventfs dput fix.

This patch set applied on top of Linux next master branch and
tested selftests ftrace tests [1]. The test run to complete and not
found any crashes.

Tested-by: Linux Kernel Functional Testing <lkft@...aro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@...aro.org>

>
> Steven Rostedt (Google) (6):
>       tracefs/eventfs: Use dput to free the toplevel events directory
>       tracing: Increase trace array ref count on enable and filter files
>       tracing: Have tracing_max_latency inc the trace array ref count
>       tracing: Have current_trace inc the trace array ref count
>       tracing: Have option files inc the trace array ref count
>       tracing: Have event inject files inc the trace array ref count
>
> ----
>  fs/tracefs/event_inode.c           | 17 +++++++---
>  fs/tracefs/inode.c                 |  2 +-
>  fs/tracefs/internal.h              |  5 +--
>  kernel/trace/trace.c               | 68 ++++++++++++++++++++++++++++++++++----
>  kernel/trace/trace.h               |  2 ++
>  kernel/trace/trace_events.c        |  6 ++--
>  kernel/trace/trace_events_inject.c |  3 +-
>  7 files changed, 85 insertions(+), 18 deletions(-)

[1] https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/naresh/tests/2V4IYQhAHrFXjwQvHLc2w3mKhXs

--
Linaro LKFT
https://lkft.linaro.org