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Subject[PATCH 1/1] tracing: fix possible null pointer dereference
Date
From: Gong Yuanjun <ruc_gongyuanjun@163.com>

In hist_trigger_elt_data_alloc(), elt_data is freed by
hist_elt_data_free() if kcalloc fails.

static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt)
{
...
elt_data->field_var_str = kcalloc(n_str, sizeof(char *), GFP_KERNEL);
if (!elt_data->field_var_str) {
hist_elt_data_free(elt_data);
return -EINVAL;
}
...}

In hist_elt_data_free() the elt_data->field_var_str field should be
checked before dereference.

Signed-off-by: Gong Yuanjun <ruc_gongyuanjun@163.com>
---
kernel/trace/trace_events_hist.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 44db5ba9cabb..73177c9f94b2 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1576,11 +1576,11 @@ static void hist_elt_data_free(struct hist_elt_data *elt_data)
{
unsigned int i;

- for (i = 0; i < elt_data->n_field_var_str; i++)
- kfree(elt_data->field_var_str[i]);
-
- kfree(elt_data->field_var_str);
-
+ if (elt_data->field_var_str) {
+ for (i = 0; i < elt_data->n_field_var_str; i++)
+ kfree(elt_data->field_var_str[i]);
+ kfree(elt_data->field_var_str);
+ }
kfree(elt_data->comm);
kfree(elt_data);
}
--
2.17.1
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