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Date: Thu, 30 Jul 2026 16:25:51 +0200
From: Greg KH <gregkh@linuxfoundation.org>
To: Mingyu Wang <25181214217@stu.xidian.edu.cn>
Cc: jirislaby@kernel.org, linux-kernel@vger.kernel.org,
	linux-serial@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] tty: vt: fix memory leak in vc_allocate()
Message-ID: <2026073028-icing-dallying-9229@gregkh>
References: <20260723070530.117552-1-25181214217@stu.xidian.edu.cn>
 <2026072345-copartner-shrink-9596@gregkh>
 <88f9ac58-8079-415d-902c-3b9455a9d17c@stu.xidian.edu.cn>
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On Thu, Jul 23, 2026 at 06:45:23PM +0800, Mingyu Wang wrote:
> 
> > How was this tested?  And how can this ever fail given this happens at
> > early boot time, right?
> > 
> 
> Hi Greg,
> 
> Thank you for the review.
> 
> Regarding how it can fail:
> While vc_allocate() is indeed heavily used during early boot, it is also
> reachable at runtime when dynamically allocating new virtual consoles (e.g.,
> via the VT_ACTIVATE ioctl). The failure we observed happened at runtime
> because our fuzzing environment enables kernel fault injection (failslab).
> The fuzzer intentionally forced the kzalloc() for the screen buffer to fail,
> which exposed this specific error-handling path.
> 
> Regarding testing:
> This issue was discovered using DevGen (our automated virtual device
> modeling fuzzer on QEMU). While we do not have a standalone C reproducer to
> run a dynamic runtime test, the fix was derived directly from dynamic
> execution evidence: we cross-analyzed the precise kmemleak backtraces and
> the fuzzer's execution logs.

You need to document the tools you use as per our documentation.  Please
do so when you resend this.

thanks,

gre gk-h