linux-kernel - Re: [patch] [bugfix] loop.c

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: <Pine.LNX.4.64.0703231522200.5030@twin.jikos.cz>
Date:	Fri, 23 Mar 2007 15:25:23 +0100 (CET)
From:	Jiri Kosina <jikos@...os.cz>
To:	Eric Dumazet <dada1@...mosbay.com>
cc:	Tomas M <tomas@...x.org>, linux-kernel@...r.kernel.org
Subject: Re: [patch] [bugfix] loop.c

On Fri, 23 Mar 2007, Eric Dumazet wrote:

> -	if (max_loop < 1 || max_loop > 256) {
> -		printk(KERN_WARNING "loop: invalid max_loop (must be between"
> -				    " 1 and 256), using default (8)\n");
> +	if (max_loop < 1) {
> +		printk(KERN_WARNING "loop: invalid max_loop (must be > 1)"
> +				    ", using default (8)\n");
>  		max_loop = 8;
>  	}
[...]
> +	loop_dev = kmalloc(max_loop * sizeof(struct loop_device *), GFP_KERNEL);
> +	if (!loop_dev) {
> +		loop_dev = vmalloc(max_loop * sizeof(struct loop_device *));
> +		if (!loop_dev)
> +			goto out_mem;
> +		loop_dev_vmalloced = 1;
>  	}

Why did you remove the upper bound check for max_loop value? Now you 
effectively allow to max_loop * sizeof(struct loop_device *) to overflow, 
when passed value of max_loop which is large enough. Or am I just blind?

The "while (nbl < max_loop)" which immediately follows is then going to 
corrupt memory, right?

-- 
Jiri Kosina
-
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/