linux-kernel - [PATCH v2 0/3] tracing: Fix synthetic event bug

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Message-ID: <20221012104055.421393330@goodmis.org>
Date:   Wed, 12 Oct 2022 06:40:55 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tom Zanussi <zanussi@...nel.org>
Subject: [PATCH v2 0/3] tracing: Fix synthetic event bug


The follow commands caused a crash:

  # cd /sys/kernel/tracing
  # echo 's:open char file[]' > dynamic_events
  # echo 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)' > events/syscalls/sys_enter_openat/trigger'
  # echo 1 > events/synthetic/open/enable

BOOM!

The problem is that the synthetic event field "char file[]" will read
the value given to it as a string without any memory checks to make sure
the address is valid. The above example will pass in the user space
address and the sythetic event code will happily call strlen() on it
and then strscpy() where either one will cause an oops when accessing
user space addresses.

Changes since v1: https://lore.kernel.org/all/20221011212501.773319898@goodmis.org/

 - Handle "(fault)" printing when there's a fault

Steven Rostedt (Google) (3):
      tracing: Move duplicate code of trace_kprobe/eprobe.c into header
      tracing: Add "(fault)" name injection to kernel probes
      tracing: Fix reading strings from synthetic events

----
 kernel/trace/trace_eprobe.c       |  60 ++------------------
 kernel/trace/trace_events_synth.c |  23 ++++++--
 kernel/trace/trace_kprobe.c       |  60 ++------------------
 kernel/trace/trace_probe_kernel.h | 115 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 142 insertions(+), 116 deletions(-)
 create mode 100644 kernel/trace/trace_probe_kernel.h