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

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Date:   Wed, 12 Oct 2022 13:46:50 +0100
From:   Masami Hiramatsu <masami.hiramatsu@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tom Zanussi <zanussi@...nel.org>
Subject: Re: [PATCH v2 0/3] tracing: Fix synthetic event bug

Hi,

2022年10月12日(水) 11:45 Steven Rostedt <rostedt@...dmis.org>:
>
>
> 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/

Thanks, this series of patches looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you!

>
>  - 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



-- 
Masami Hiramatsu
mailto:masami.hiramatsu@...il.com