[PATCH 3/8] tracing: fprobe-events: Log error for exceeding the number of entry args

Masami Hiramatsu (Google)
2025-02-26T06:19:05Z

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

Add error message when the number of entry argument exceeds the
maximum size of entry data.
This is currently checked when registering fprobe, but in this case
no error message is shown in the error_log file.

Fixes: 25f00e40ce79 ("tracing/probes: Support $argN in return probe (kprobe and fprobe)")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
kernel/trace/trace_fprobe.c | 5 +++++
kernel/trace/trace_probe.h | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 85f037dc1462..e27305d31fc5 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1230,6 +1230,11 @@ static int trace_fprobe_create_internal(int argc, const char *argv[],
if (is_return && tf->tp.entry_arg) {
tf->fp.entry_handler = trace_fprobe_entry_handler;
tf->fp.entry_data_size = traceprobe_get_entry_data_size(&tf->tp);
+ if (ALIGN(tf->fp.entry_data_size, sizeof(long)) > MAX_FPROBE_DATA_SIZE) {
+ trace_probe_log_set_index(2);
+ trace_probe_log_err(0, TOO_MANY_EARGS);
+ return -E2BIG;
+ }
}

ret = traceprobe_set_print_fmt(&tf->tp,
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index fba3ede87054..c47ca002347a 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -545,7 +545,8 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
C(NO_BTF_FIELD, "This field is not found."), \
C(BAD_BTF_TID, "Failed to get BTF type info."),\
C(BAD_TYPE4STR, "This type does not fit for string."),\
- C(NEED_STRING_TYPE, "$comm and immediate-string only accepts string type"),
+ C(NEED_STRING_TYPE, "$comm and immediate-string only accepts string type"),\
+ C(TOO_MANY_EARGS, "Too many entry arguments specified"),

#undef C
#define C(a, b) TP_ERR_##a