* [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops()
@ 2022-05-08 16:18 Jeff Xie
2022-05-09 1:33 ` Jeff Xie
0 siblings, 1 reply; 4+ messages in thread
From: Jeff Xie @ 2022-05-08 16:18 UTC (permalink / raw)
To: rostedt; +Cc: mingo, mhiramat, zanussi, linux-kernel, Jeff Xie
Currently if the ftrace_allocate_ftrace_ops() return -ENOMEM,
the ftrace_free_ftrace_ops() will kfree(NULL).
trace_array_create()
{
...
if (ftrace_allocate_ftrace_ops(tr) < 0)
goto out_free_tr;
...
out_free_tr:
ftrace_free_ftrace_ops(tr);
...
}
ftrace_allocate_ftrace_ops()
{
...
ops = kzalloc(sizeof(*ops), GFP_KERNEL);
if (!ops)
return -ENOMEM;
...
}
ftrace_free_ftrace_ops()
{
kfree(tr->ops);
tr->ops = NULL;
}
Signed-off-by: Jeff Xie <xiehuan09@gmail.com>
---
kernel/trace/trace_functions.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 9f1bfbe105e8..d186d6101695 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -73,6 +73,9 @@ int ftrace_allocate_ftrace_ops(struct trace_array *tr)
void ftrace_free_ftrace_ops(struct trace_array *tr)
{
+ if (!tr->ops)
+ return;
+
kfree(tr->ops);
tr->ops = NULL;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops()
2022-05-08 16:18 [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops() Jeff Xie
@ 2022-05-09 1:33 ` Jeff Xie
2022-05-09 7:34 ` Ammar Faizi
2022-05-09 22:54 ` Steven Rostedt
0 siblings, 2 replies; 4+ messages in thread
From: Jeff Xie @ 2022-05-09 1:33 UTC (permalink / raw)
To: Steven Rostedt; +Cc: mingo, Masami Hiramatsu, Tom Zanussi, linux-kernel
I am so sorry to bother you, this may be an invalid patch, kfree can
return directly from null. ;-)
On Mon, May 9, 2022 at 12:18 AM Jeff Xie <xiehuan09@gmail.com> wrote:
>
> Currently if the ftrace_allocate_ftrace_ops() return -ENOMEM,
> the ftrace_free_ftrace_ops() will kfree(NULL).
>
> trace_array_create()
> {
> ...
> if (ftrace_allocate_ftrace_ops(tr) < 0)
> goto out_free_tr;
> ...
> out_free_tr:
> ftrace_free_ftrace_ops(tr);
> ...
> }
>
> ftrace_allocate_ftrace_ops()
> {
> ...
> ops = kzalloc(sizeof(*ops), GFP_KERNEL);
> if (!ops)
> return -ENOMEM;
> ...
> }
>
> ftrace_free_ftrace_ops()
> {
> kfree(tr->ops);
> tr->ops = NULL;
> }
>
> Signed-off-by: Jeff Xie <xiehuan09@gmail.com>
> ---
> kernel/trace/trace_functions.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index 9f1bfbe105e8..d186d6101695 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -73,6 +73,9 @@ int ftrace_allocate_ftrace_ops(struct trace_array *tr)
>
> void ftrace_free_ftrace_ops(struct trace_array *tr)
> {
> + if (!tr->ops)
> + return;
> +
> kfree(tr->ops);
> tr->ops = NULL;
> }
> --
> 2.25.1
>
Thanks,
JeffXie
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops()
2022-05-09 1:33 ` Jeff Xie
@ 2022-05-09 7:34 ` Ammar Faizi
2022-05-09 22:54 ` Steven Rostedt
1 sibling, 0 replies; 4+ messages in thread
From: Ammar Faizi @ 2022-05-09 7:34 UTC (permalink / raw)
To: Jeff Xie
Cc: Ingo Molnar, Masami Hiramatsu, Steven Rostedt, Tom Zanussi,
Linux Kernel Mailing List
On 5/9/22 8:33 AM, Jeff Xie wrote:
> I am so sorry to bother you, this may be an invalid patch, kfree can
> return directly from null. ;-)
Yeah, kfree(NULL) is a valid call. There's no potential crash here.
--
Ammar Faizi
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops()
2022-05-09 1:33 ` Jeff Xie
2022-05-09 7:34 ` Ammar Faizi
@ 2022-05-09 22:54 ` Steven Rostedt
1 sibling, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2022-05-09 22:54 UTC (permalink / raw)
To: Jeff Xie; +Cc: mingo, Masami Hiramatsu, Tom Zanussi, linux-kernel
On Mon, 9 May 2022 09:33:44 +0800
Jeff Xie <xiehuan09@gmail.com> wrote:
> I am so sorry to bother you, this may be an invalid patch, kfree can
> return directly from null. ;-)
Yes, and so does free() in user space glibc.
-- Steve
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-05-09 22:54 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-08 16:18 [PATCH] tracing: Fix possible crash in ftrace_free_ftrace_ops() Jeff Xie
2022-05-09 1:33 ` Jeff Xie
2022-05-09 7:34 ` Ammar Faizi
2022-05-09 22:54 ` Steven Rostedt
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