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Message-ID: <a5a79265-be08-0375-ad50-fbe568c7a769@huawei.com>
Date:   Mon, 7 Nov 2022 19:45:04 +0800
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Subject: Re: [PATCH v2] tracing: fix memory leak in tracing_read_pipe
To:     <linux-kernel@vger.kernel.org>
CC:     <rostedt@goodmis.org>, <mhiramat@kernel.org>
References: <1667819090-4643-1-git-send-email-wangyufen@huawei.com>
From:   wangyufen <wangyufen@huawei.com>
In-Reply-To: <1667819090-4643-1-git-send-email-wangyufen@huawei.com>
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在 2022/11/7 19:04, Wang Yufen 写道:
> kmemleak reports this issue:
>
> unreferenced object 0xffff888105a18900 (size 128):
>    comm "test_progs", pid 18933, jiffies 4336275356 (age 22801.766s)
>    hex dump (first 32 bytes):
>      25 73 00 90 81 88 ff ff 26 05 00 00 42 01 58 04  %s......&...B.X.
>      03 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00  ................
>    backtrace:
>      [<00000000560143a1>] __kmalloc_node_track_caller+0x4a/0x140
>      [<000000006af00822>] krealloc+0x8d/0xf0
>      [<00000000c309be6a>] trace_iter_expand_format+0x99/0x150
>      [<000000005a53bdb6>] trace_check_vprintf+0x1e0/0x11d0
>      [<0000000065629d9d>] trace_event_printf+0xb6/0xf0
>      [<000000009a690dc7>] trace_raw_output_bpf_trace_printk+0x89/0xc0
>      [<00000000d22db172>] print_trace_line+0x73c/0x1480
>      [<00000000cdba76ba>] tracing_read_pipe+0x45c/0x9f0
>      [<0000000015b58459>] vfs_read+0x17b/0x7c0
>      [<000000004aeee8ed>] ksys_read+0xed/0x1c0
>      [<0000000063d3d898>] do_syscall_64+0x3b/0x90
>      [<00000000a06dda7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> iter->fmt alloced in
>    tracing_read_pipe() -> .. ->trace_iter_expand_format(), but not
> freed, to fix, add free in tracing_release_pipe()
Fixes: efbbdaa22bb7 ("tracing: Show real address for trace event arguments")
> Signed-off-by: Wang Yufen <wangyufen@huawei.com>
> ---
> v1 -> v2: del if (iter->fmt), free iter->fmt directly
>   kernel/trace/trace.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 47a44b0..f9d98e7 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -6657,6 +6657,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file)
>   	mutex_unlock(&trace_types_lock);
>   
>   	free_cpumask_var(iter->started);
> +	kfree(iter->fmt);
>   	mutex_destroy(&iter->mutex);
>   	kfree(iter);
>