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Message-ID: <20230713103353.29cae218@gandalf.local.home>
Date: Thu, 13 Jul 2023 10:33:53 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Zheng Yejian <zhengyejian1@...wei.com>
Cc: <mhiramat@...nel.org>, <linux-kernel@...r.kernel.org>,
<linux-trace-kernel@...r.kernel.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
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 <zhengyejian1@...wei.com> 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 <zhengyejian1@...wei.com>
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);
>
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