linux-kernel - Re: [PATCH RESEND] binder: handle PID namespace conversion for freeze operation

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Message-Id: <20260119005607.11352-1-jongan.kim@lge.com>
Date: Mon, 19 Jan 2026 09:56:07 +0900
From: jongan.kim@....com
To: aliceryhl@...gle.com
Cc: arve@...roid.com,
	brauner@...nel.org,
	cmllamas@...gle.com,
	gregkh@...uxfoundation.org,
	heesu0025.kim@....com,
	ht.hong@....com,
	jongan.kim@....com,
	jungsu.hwang@....com,
	kernel-team@...roid.com,
	linux-kernel@...r.kernel.org,
	sanghun.lee@....com,
	seulgi.lee@....com,
	sunghoon.kim@....com,
	tkjos@...roid.com
Subject: Re: [PATCH RESEND] binder: handle PID namespace conversion for freeze operation

Alice Ryhl @ 2026-01-16 10:52 UTC wrote:
> On Fri, Jan 16, 2026 at 02:52:22PM +0900, jongan.kim@....com wrote:
> > Alice Ryhl @ 2026-01-15  8:41 UTC wrote:
> > > On Thu, Jan 15, 2026 at 05:06:19PM +0900, jongan.kim@....com wrote:
> > > > As Alice mentioned, since only the freeze operation takes a pid as input, it
> > > > receives the local pid of the namespace. This patch converts this pid to the
> > > > global pid of the init namespace for matching pid of binder_procs properly.
> > > > (binder_procs has `task->group_leader->pid`). Are there any concerns or 
> > > > problems for this logic?
> > >
> > > This isn't new with your changes ... but it does have a race where the
> > > target process dies and gets replaced by a new process with the same pid
> > > just before you invoke the freeze ioctl.
> > 
> > Thanks for sharing! Has this issue been encountered before? I think there may
> > be a potential problem, although it is very unlikely to occur. (It is also very
> > hard to fix and verify the problem I guess...)
> > For now I want to focus on the patch submitted regarding the PID namespace on
> > this thread. Please check if there are any issues with merging this patch into
> > the binder driver.
> 
> I do think it makes sense for freeze to convert pids like this. The Rust
> driver should also be updated with the same change at the same time.

Thanks for confirmation. I will update the patch after changing and verifying
the rust driver.

Thanks. // JongAn, Kim