linux-kernel - Re: [PATCH v2] tty: serial: fsl_lpuart.c: prevent a bad shift operation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200729160333.GA3652767@kroah.com>
Date:   Wed, 29 Jul 2020 18:03:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     B K Karthik <bkkarthik@...u.pes.edu>
Cc:     Jiri Slaby <jirislaby@...nel.org>, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Vabhav Sharma (OSS)" <vabhav.sharma@....nxp.com>,
        "bhuvanchandra.dv@...adex.com" <bhuvanchandra.dv@...adex.com>
Subject: Re: [PATCH v2] tty: serial: fsl_lpuart.c: prevent a bad shift
 operation

On Tue, Jul 21, 2020 at 11:12:29PM +0530, B K Karthik wrote:
> prevent a bad shift operation by verifying that
> the argument to fls is non zero.
> 
> Reported-by: "Vabhav Sharma (OSS)" <vabhav.sharma@....nxp.com>
> Signed-off-by: B K Karthik <bkkarthik@...u.pes.edu>
> ---
> v1 -> v2:
> 	added Reported-by tag
> 
>  drivers/tty/serial/fsl_lpuart.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index 7ca642249224..0cc64279cd2d 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1168,7 +1168,8 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
>  	 * 10ms at any baud rate.
>  	 */
>  	sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud /  bits / 1000) * 2;
> -	sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
> +	if (sport->rx_dma_rng_buf_len != 0)

How can this variable become 0?

thanks,

greg k-h