On Tue, 11 Jul 2023 23:16:07 +0900
"Masami Hiramatsu (Google)" [off-list ref] wrote:

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

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@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 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@goodmis.org>

-- Steve