linux-kernel - Re: [PATCH 3/3] tty: hvc: hvc

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] [day] [month] [year] [list]

Message-ID: <20180906231039.7b71186a@roar.ozlabs.ibm.com>
Date:   Thu, 6 Sep 2018 23:10:39 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jiri Slaby <jslaby@...e.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Matteo Croce <mcroce@...hat.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org (op)
Subject: Re: [PATCH 3/3] tty: hvc: hvc_write() fix break condition

On Wed,  5 Sep 2018 22:14:39 +1000
Nicholas Piggin <npiggin@...il.com> wrote:

> Commit 550ddadcc758 ("tty: hvc: hvc_write() may sleep") broke the
> termination condition in case the driver stops accepting characters.
> This can result in unnecessary polling of the busy driver.
> 
> Restore it by testing the hvc_push return code.
> 
> Fixes: 550ddadcc758 ("tty: hvc: hvc_write() may sleep")
> Tested-by: Matteo Croce <mcroce@...hat.com>
> Tested-by: Leon Romanovsky <leonro@...lanox.com>
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
>  drivers/tty/hvc/hvc_console.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
> index bacf9b73ec98..c09a38fb0d66 100644
> --- a/drivers/tty/hvc/hvc_console.c
> +++ b/drivers/tty/hvc/hvc_console.c
> @@ -522,6 +522,8 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count
>  		return -EIO;
>  
>  	while (count > 0) {
> +		int ret;
> +
>  		spin_lock_irqsave(&hp->lock, flags);
>  
>  		rsize = hp->outbuf_size - hp->n_outbuf;

That needs to be 'int ret = 0;' to avoid used uninitialized.

Let me know if I should resend the patches.

Thanks,
Nick