linux-kernel - Re: [PATCH 28/49] tty: Add a new file /proc/tty/consoles

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: <4CC2C9A8.1040003@suse.cz>
Date:	Sat, 23 Oct 2010 13:40:24 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Greg Kroah-Hartman <gregkh@...e.de>
CC:	linux-kernel@...r.kernel.org, "Dr. Werner Fink" <werner@...e.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 28/49] tty: Add a new file /proc/tty/consoles

On 10/22/2010 08:21 PM, Greg Kroah-Hartman wrote:
> +/*
> + * Used for open /proc/tty/consoles. Before this detect
> + * the device ID of file descriptor 0 of the current
> + * reading task if a character device...
> + */
> +static int tty_consoles_open(struct inode *inode, struct file *file)
> +{
> +	struct files_struct *curfiles;
> +
> +	current_dev = 0;
> +	curfiles = get_files_struct(current);
> +	if (curfiles) {
> +		const struct file *curfp;
> +		spin_lock(&curfiles->file_lock);
> +		curfp = fcheck_files(curfiles, 0);
> +		if (curfp && curfp->private_data) {
> +			const struct inode *inode;
> +			dget(curfp->f_dentry);
> +			inode = curfp->f_dentry->d_inode;
> +			if (S_ISCHR(inode->i_mode)) {
> +				struct tty_struct *tty;
> +				tty = (struct tty_struct *)curfp->private_data;
> +				if (tty && tty->magic == TTY_MAGIC) {

Ah, I've just understood what this code does. It seems, that the 'tty'
at this point may be already freed (e.g. people don't set private_data
to NULL). Please explain in the code why it can't...

Maybe I wouldn't bother with marking the "current" console by star at
all as it seems not to pay off.

> +					tty = tty_pair_get_tty(tty);
> +					current_dev = tty_devnum(tty);
> +				}
> +			}
> +			dput(curfp->f_dentry);
> +		}
> +		spin_unlock(&curfiles->file_lock);
> +		put_files_struct(curfiles);
> +	}
> +	return seq_open(file, &tty_consoles_op);
> +}

regards,
-- 
js
suse labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/