linux-kernel - Re: [PATCH] serial: 8250_pci: Fix uninitialized variable use in pci_oxsemi_tornado_get

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Message-ID: <2026012141-arrival-mounted-0d49@gregkh>
Date: Wed, 21 Jan 2026 17:36:58 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Lee Yongjun <jun85566@...il.com>
Cc: Jiri Slaby <jirislaby@...nel.org>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] serial: 8250_pci: Fix uninitialized variable use in
 pci_oxsemi_tornado_get_divisor

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