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Date: Sun, 30 Oct 2022 10:31:02 -0400
From: Rich Felker <>
To: puwenxu <>
Cc: "" <>
Subject: Re: Question on 2b2c8aafce9d80f9d58652643538f4d58e82b856

On Sun, Oct 30, 2022 at 06:29:54AM +0000, puwenxu wrote:
> Dear maintainer,
>        I'm using musl now. When I was running some test case
> codes for musl, I found there may be a problem on modification of
> 2b2c8aafce9d80f9d58652643538f4d58e82b856.
>        As you can see in the picture, this modification assign buf
> to orig. Then, the orig will be assigned to buf again. If the
> original value of buf is NULL, the latter value of the buf will be
> NULL. However, assign out to buf will fail if buf is NULL.

Rather than pointing at what you think is wrong in the source change,
can you demonstrate a minimal example of calling code that was correct
and worked before the change, but fails after the change?

As best I can tell, your concern is about the case where you pass a
null pointer as buf when using one of the msgctl commands that
requires a pointer to a buffer. This is undefined.

>        I have written a simple file to verification my opinion. The
> test code and output is shown in the following picture. I think it
> may be better to add a check for buf in this situation.

This isn't an example. An example would be a minimal program that
calls msgctl in a valid (i.e. no undefined behavior) way and
malfunctions as a result of the change.


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