linux-kernel - Re: TTY: ntty, add one more sanity check

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Message-ID: <4DEE6037.1020400@suse.cz>
Date:	Tue, 07 Jun 2011 19:30:31 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Greg KH <greg@...ah.com>
CC:	gregkh@...e.de, jirislaby@...il.com, linux-kernel@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: TTY: ntty, add one more sanity check

On 06/07/2011 07:20 PM, Greg KH wrote:
> On Sun, Jun 05, 2011 at 02:16:17PM +0200, Jiri Slaby wrote:
>> With the previous patch, we fixed another bug where read_buf was freed
>> while we still was in n_tty_read. We currently check whether read_buf
>> is NULL at the start of the function. Add one more check after we wake
>> up from waiting for input.
>>
>> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
>> Cc: Alan Cox <alan@...rguk.ukuu.org.uk>
>> ---
>>  drivers/tty/n_tty.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
>> index 95d0a9c..c62c856 100644
>> --- a/drivers/tty/n_tty.c
>> +++ b/drivers/tty/n_tty.c
>> @@ -1785,6 +1785,7 @@ do_it_again:
>>  				break;
>>  			}
>>  			timeout = schedule_timeout(timeout);
>> +			BUG_ON(!tty->read_buf);
>>  			continue;
>>  		}
>>  		__set_current_state(TASK_RUNNING);
> 
> This doesn't apply anymore without some fuzz as stuff has changed in
> this area in Linus's tree.
> 
> Can you refresh it and resend it so that I know it's correct?
> 
> Or, just verify that the diff below is correct, and I'll take that one.

Yes, it's correct.

> thanks,
> 
> greg k-h
> 
> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
> index 0ad3288..c3954fb 100644
> --- a/drivers/tty/n_tty.c
> +++ b/drivers/tty/n_tty.c
> @@ -1815,6 +1815,7 @@ do_it_again:
>  			/* FIXME: does n_tty_set_room need locking ? */
>  			n_tty_set_room(tty);
>  			timeout = schedule_timeout(timeout);
> +			BUG_ON(!tty->read_buf);
>  			continue;
>  		}
>  		__set_current_state(TASK_RUNNING);

thanks,
-- 
js
suse labs
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