Re: [PATCH v5 5/5] tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails

[Steven Rostedt]

On Tue, 11 Jul 2023 23:16:07 +0900
"Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> 
> Fix to record 0-length data to data_loc in fetch_store_string*() if it fails
> to get the string data.
> Currently those expect that the data_loc is updated by store_trace_args() if
> it returns the error code. However, that does not work correctly if the
> argument is an array of strings. In that case, store_trace_args() only clears
> the first entry of the array (which may have no error) and leaves other
> entries. So it should be cleared by fetch_store_string*() itself.
> Also, 'dyndata' and 'maxlen' in store_trace_args() should be updated
> only if it is used (ret > 0 and argument is a dynamic data.)
> 
> Fixes: 40b53b771806 ("tracing: probeevent: Add array type support")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> ---
>  Changes in v4:
>   - Simplify the updating data_loc code with set_data_loc().
>  Changes in v5:
>   - Move out arg->dynamic check from unlikely() and use likely().
> ---
>  kernel/trace/trace_probe_kernel.h |   13 +++++++++----
>  kernel/trace/trace_probe_tmpl.h   |   10 +++-------
>  kernel/trace/trace_uprobe.c       |    3 ++-
>  3 files changed, 14 insertions(+), 12 deletions(-)
> 


Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>

-- Steve