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

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Message-ID: <aWoYeQcg-OYcglIf@google.com>
Date: Fri, 16 Jan 2026 10:52:41 +0000
From: Alice Ryhl <aliceryhl@...gle.com>
To: jongan.kim@....com
Cc: gregkh@...uxfoundation.org, arve@...roid.com, brauner@...nel.org, 
	cmllamas@...gle.com, heesu0025.kim@....com, ht.hong@....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

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.

Alice