linux-kernel - [PATCH] tracing: Fix memory leaks in create_field

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Message-Id: <20251106120132.3639920-1-zilin@seu.edu.cn>
Date: Thu,  6 Nov 2025 12:01:32 +0000
From: Zilin Guan <zilin@....edu.cn>
To: rostedt@...dmis.org
Cc: mhiramat@...nel.org,
	mathieu.desnoyers@...icios.com,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	jianhao.xu@....edu.cn,
	Zilin Guan <zilin@....edu.cn>
Subject: [PATCH] tracing: Fix memory leaks in create_field_var()

The function create_field_var() allocates memory for 'val' through
create_hist_field() inside parse_atom(), and for 'var' through
create_var(), which in turn allocates var->type and var->var.name
internally. Simply calling kfree() to release these structures will
result in memory leaks.

Use destroy_hist_field() to properly free 'val', and explicitly release
the memory of var->type and var->var.name before freeing 'var' itself.

Fixes: 02205a6752f22 ("tracing: Add support for 'field variables'")
Signed-off-by: Zilin Guan <zilin@....edu.cn>
---
 kernel/trace/trace_events_hist.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 1d536219b624..6bfaf1210dd2 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3272,14 +3272,16 @@ static struct field_var *create_field_var(struct hist_trigger_data *hist_data,
 	var = create_var(hist_data, file, field_name, val->size, val->type);
 	if (IS_ERR(var)) {
 		hist_err(tr, HIST_ERR_VAR_CREATE_FIND_FAIL, errpos(field_name));
-		kfree(val);
+		destroy_hist_field(val, 0);
 		ret = PTR_ERR(var);
 		goto err;
 	}
 
 	field_var = kzalloc(sizeof(struct field_var), GFP_KERNEL);
 	if (!field_var) {
-		kfree(val);
+		destroy_hist_field(val, 0);
+		kfree_const(var->type);
+		kfree(var->var.name);
 		kfree(var);
 		ret =  -ENOMEM;
 		goto err;
-- 
2.34.1