From: Greg KH <gregkh@linuxfoundation.org>
To: Weigang He <geoffreyhe2@gmail.com>
Cc: mathias.nyman@intel.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] usb: xhci: fix missing null termination after copy_from_user()
Date: Sat, 17 Jan 2026 10:58:41 +0100 [thread overview]
Message-ID: <2026011725-ecosystem-proved-a6ba@gregkh> (raw)
In-Reply-To: <20260117094631.504232-1-geoffreyhe2@gmail.com>
On Sat, Jan 17, 2026 at 09:46:31AM +0000, Weigang He wrote:
> The buffer 'buf' is filled by copy_from_user() but is not properly
> null-terminated before being used with strncmp(). If userspace provides
> fewer than 10 bytes, strncmp() may read beyond the copied data into
> uninitialized stack memory.
But that's fine, it will not match the check, and so it will stop when
told, so no overflow happens anywhere.
> Add explicit null termination after copy_from_user() to ensure the
> buffer is always a valid C string before string operations.
It's ok, and is valid, and this is all debugging code. This isn't a
real bug, sorry.
> Fixes: 87a03802184c ("xhci: debugfs: add debugfs interface to enable compliance mode for a port")
> Cc: stable@vger.kernel.org
Nope, this doesn't "fix" anything.
How was this bug found? What tool did you use for this? How was it tested?
thanks,
greg k-h
next prev parent reply other threads:[~2026-01-17 9:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-17 9:46 [PATCH] usb: xhci: fix missing null termination after copy_from_user() Weigang He
2026-01-17 9:58 ` Greg KH [this message]
[not found] ` <SE1P216MB1822A187820001789CB4EE3AF28AA@SE1P216MB1822.KORP216.PROD.OUTLOOK.COM>
2026-01-17 10:25 ` Greg KH
2026-01-17 12:06 ` David Laight
2026-01-17 12:17 ` Greg KH
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