2023-07-13 14:40:30

by Zheng Yejian

[permalink] [raw]
Subject: [PATCH] traing: Fix memory leak of iter->temp when reading trace_pipe

kmemleak reports:
unreferenced object 0xffff88814d14e200 (size 256):
comm "cat", pid 336, jiffies 4294871818 (age 779.490s)
hex dump (first 32 bytes):
04 00 01 03 00 00 00 00 08 00 00 00 00 00 00 00 ................
0c d8 c8 9b ff ff ff ff 04 5a ca 9b ff ff ff ff .........Z......
backtrace:
[<ffffffff9bdff18f>] __kmalloc+0x4f/0x140
[<ffffffff9bc9238b>] trace_find_next_entry+0xbb/0x1d0
[<ffffffff9bc9caef>] trace_print_lat_context+0xaf/0x4e0
[<ffffffff9bc94490>] print_trace_line+0x3e0/0x950
[<ffffffff9bc95499>] tracing_read_pipe+0x2d9/0x5a0
[<ffffffff9bf03a43>] vfs_read+0x143/0x520
[<ffffffff9bf04c2d>] ksys_read+0xbd/0x160
[<ffffffff9d0f0edf>] do_syscall_64+0x3f/0x90
[<ffffffff9d2000aa>] entry_SYSCALL_64_after_hwframe+0x6e/0xd8

when reading file 'trace_pipe', 'iter->temp' is allocated or relocated
in trace_find_next_entry() but not freed before 'trace_pipe' is closed.

To fix it, free 'iter->temp' in tracing_release_pipe().

Signed-off-by: Zheng Yejian <[email protected]>
---
kernel/trace/trace.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4529e264cb86..94cfaa884578 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6764,6 +6764,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)

free_cpumask_var(iter->started);
kfree(iter->fmt);
+ kfree(iter->temp);
mutex_destroy(&iter->mutex);
kfree(iter);

--
2.25.1



2023-07-13 14:52:53

by Steven Rostedt

[permalink] [raw]
Subject: Re: [PATCH] traing: Fix memory leak of iter->temp when reading trace_pipe

On Thu, 13 Jul 2023 22:14:35 +0800
Zheng Yejian <[email protected]> wrote:

> kmemleak reports:
> unreferenced object 0xffff88814d14e200 (size 256):
> comm "cat", pid 336, jiffies 4294871818 (age 779.490s)
> hex dump (first 32 bytes):
> 04 00 01 03 00 00 00 00 08 00 00 00 00 00 00 00 ................
> 0c d8 c8 9b ff ff ff ff 04 5a ca 9b ff ff ff ff .........Z......
> backtrace:
> [<ffffffff9bdff18f>] __kmalloc+0x4f/0x140
> [<ffffffff9bc9238b>] trace_find_next_entry+0xbb/0x1d0
> [<ffffffff9bc9caef>] trace_print_lat_context+0xaf/0x4e0
> [<ffffffff9bc94490>] print_trace_line+0x3e0/0x950
> [<ffffffff9bc95499>] tracing_read_pipe+0x2d9/0x5a0
> [<ffffffff9bf03a43>] vfs_read+0x143/0x520
> [<ffffffff9bf04c2d>] ksys_read+0xbd/0x160
> [<ffffffff9d0f0edf>] do_syscall_64+0x3f/0x90
> [<ffffffff9d2000aa>] entry_SYSCALL_64_after_hwframe+0x6e/0xd8
>
> when reading file 'trace_pipe', 'iter->temp' is allocated or relocated
> in trace_find_next_entry() but not freed before 'trace_pipe' is closed.
>
> To fix it, free 'iter->temp' in tracing_release_pipe().
>
> Signed-off-by: Zheng Yejian <[email protected]>

Why is it that every time I send a pull request to Linus, I get another fix???

Anyway, Linus, hold off. I'll send a v3 with this included as well.

-- Steve

> ---
> kernel/trace/trace.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 4529e264cb86..94cfaa884578 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6764,6 +6764,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
>
> free_cpumask_var(iter->started);
> kfree(iter->fmt);
> + kfree(iter->temp);
> mutex_destroy(&iter->mutex);
> kfree(iter);
>


2023-07-13 15:01:58

by Steven Rostedt

[permalink] [raw]
Subject: Re: [PATCH] traing: Fix memory leak of iter->temp when reading trace_pipe

On Thu, 13 Jul 2023 14:44:04 +0000
"Zhengyejian (Zetta)" <[email protected]> wrote:

> Hi, Steve,
>
> Please correct a typo in title: trainy -> tracing

traing -> tracing ;-)

>
> I'm a little hurry home from work :(
> I'll pay attention to it next time.

No problem. I made the fix.

But seriously, thanks for all the fixes you are sending my way!

-- Steve


2023-07-14 01:57:50

by Zheng Yejian

[permalink] [raw]
Subject: Re: [PATCH] traing: Fix memory leak of iter->temp when reading trace_pipe

On 2023/7/13 22:51, Steven Rostedt wrote:
> On Thu, 13 Jul 2023 14:44:04 +0000
> "Zhengyejian (Zetta)" <[email protected]> wrote:
>
>> Hi, Steve,
>>
>> Please correct a typo in title: trainy -> tracing
>
> traing -> tracing ;-)

Emm, my anothor typo 'trainy'. Phone's keyboard is hard to use :)

>
>>
>> I'm a little hurry home from work :(
>> I'll pay attention to it next time.
>
> No problem. I made the fix.
>
> But seriously, thanks for all the fixes you are sending my way!
>

You're welcome! I am happy to do it and have learned a lot :)

> -- Steve
>
>
--
Thanks,
Zheng Yejian