* [PATCH 1/1] tracing: fix possible null pointer dereference
@ 2022-05-17 9:57 Yuanjun Gong
2022-05-17 10:06 ` Greg KH
2022-05-18 19:28 ` Steven Rostedt
0 siblings, 2 replies; 3+ messages in thread
From: Yuanjun Gong @ 2022-05-17 9:57 UTC (permalink / raw)
To: Yuanjun Gong, Steven Rostedt, Ingo Molnar, linux-kernel; +Cc: stable
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] tracing: fix possible null pointer dereference
2022-05-17 9:57 [PATCH 1/1] tracing: fix possible null pointer dereference Yuanjun Gong
@ 2022-05-17 10:06 ` Greg KH
2022-05-18 19:28 ` Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Greg KH @ 2022-05-17 10:06 UTC (permalink / raw)
To: Yuanjun Gong; +Cc: Steven Rostedt, Ingo Molnar, linux-kernel, stable
On Tue, May 17, 2022 at 05:57:23PM +0800, Yuanjun Gong wrote:
> 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
>
<formletter>
This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.
</formletter>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] tracing: fix possible null pointer dereference
2022-05-17 9:57 [PATCH 1/1] tracing: fix possible null pointer dereference Yuanjun Gong
2022-05-17 10:06 ` Greg KH
@ 2022-05-18 19:28 ` Steven Rostedt
1 sibling, 0 replies; 3+ messages in thread
From: Steven Rostedt @ 2022-05-18 19:28 UTC (permalink / raw)
To: Yuanjun Gong; +Cc: Ingo Molnar, linux-kernel, stable
On Tue, 17 May 2022 17:57:23 +0800
Yuanjun Gong <ruc_gongyuanjun@163.com> wrote:
> 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) {
But at this position elt_data->n_field_var_str is zero.
> 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++)
This loop will not execute because n_field_var_str is zero, and 0 < 0 is
false.
> - kfree(elt_data->field_var_str[i]);
> -
> - kfree(elt_data->field_var_str);
freeing a NULL pointer is OK to do.
There is nothing wrong with the current code. NACK.
-- Steve
> -
> + 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);
> }
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-05-17 10:06 ` Greg KH
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