[PATCH] tracing: Fix memory leaks in create_field_var()

[Zilin Guan]

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 <zi...@seu.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