From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Lee Yongjun <jun85566@gmail.com>
Cc: Jiri Slaby <jirislaby@kernel.org>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH] serial: 8250_pci: Fix uninitialized variable use in pci_oxsemi_tornado_get_divisor
Date: Wed, 21 Jan 2026 17:36:58 +0100 [thread overview]
Message-ID: <2026012141-arrival-mounted-0d49@gregkh> (raw)
In-Reply-To: <20260121155352.52489-1-jun85566@gmail.com>
On Thu, Jan 22, 2026 at 12:53:52AM +0900, Lee Yongjun wrote:
> Smatch reports the following errors:
>
> drivers/tty/serial/8250/8250_pci.c:1246 pci_oxsemi_tornado_get_divisor() error: uninitialized symbol 'tcr'.
> drivers/tty/serial/8250/8250_pci.c:1247 pci_oxsemi_tornado_get_divisor() error: uninitialized symbol 'quot'.
> drivers/tty/serial/8250/8250_pci.c:1251 pci_oxsemi_tornado_get_divisor() error: uninitialized symbol 'quot'.
> drivers/tty/serial/8250/8250_pci.c:1255 pci_oxsemi_tornado_get_divisor() error: uninitialized symbol 'cpr'.
> drivers/tty/serial/8250/8250_pci.c:1265 pci_oxsemi_tornado_get_divisor() error: uninitialized symbol 'cpr'.
>
> These variables are initialized in the if branch or inside the loop in
> the else branch. However, if the loop finishes without finding a suitable
> divisor, they remain uninitialized.
But can that ever really happen? Please step through it all with the
values that the hardware provides to see this.
> Initialize 'quot', 'cpr', and 'tcr' to 0 to prevent undefined behavior.
Why haven't we seen any real problems with this? I think this is ok
as-is. Maybe a little bit complex and non-intutive, but ok.
thanks,
greg k-h
next prev parent reply other threads:[~2026-01-21 16:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-21 15:53 [PATCH] serial: 8250_pci: Fix uninitialized variable use in pci_oxsemi_tornado_get_divisor Lee Yongjun
2026-01-21 16:36 ` Greg Kroah-Hartman [this message]
2026-01-22 0:18 ` Lee Yongjun
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