netdev - Re: [patch] isdn: fix information leak

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Date:	Thu, 5 Aug 2010 18:08:08 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Dan Carpenter <error27@...il.com>
Cc:	Karsten Keil <isdn@...ux-pingi.de>, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] isdn: fix information leak

On Thu, Aug 5, 2010 at 5:38 PM, Dan Carpenter <error27@...il.com> wrote:
> The main motivation of this patch changing strcpy() to strlcpy().
> We strcpy() to copy a 48 byte buffers into a 49 byte buffers.  So at
> best the last byte has leaked information, or maybe there is an
> overflow?  Anyway, this patch closes the information leaks by zeroing
> the memory and the calls to strlcpy() prevent overflows.

strlcpy() can handle the terminator NUL. so you don't need to zero it.

>
> Signed-off-by: Dan Carpenter <error27@...il.com>
>
> diff --git a/drivers/isdn/sc/ioctl.c b/drivers/isdn/sc/ioctl.c
> index 1081091..2655e3a 100644
> --- a/drivers/isdn/sc/ioctl.c
> +++ b/drivers/isdn/sc/ioctl.c
> @@ -174,7 +174,7 @@ int sc_ioctl(int card, scs_ioctl *data)
>                pr_debug("%s: SCIOGETSPID: ioctl received\n",
>                                sc_adapter[card]->devicename);
>
> -               spid = kmalloc(SCIOC_SPIDSIZE, GFP_KERNEL);
> +               spid = kzalloc(SCIOC_SPIDSIZE, GFP_KERNEL);
>                if (!spid) {
>                        kfree(rcvmsg);
>                        return -ENOMEM;
> @@ -194,7 +194,7 @@ int sc_ioctl(int card, scs_ioctl *data)
>                        kfree(rcvmsg);
>                        return status;
>                }
> -               strcpy(spid, rcvmsg->msg_data.byte_array);
> +               strlcpy(spid, rcvmsg->msg_data.byte_array, SCIOC_SPIDSIZE);
>
>                /*
>                 * Package the switch type and send to user space
> @@ -272,12 +272,12 @@ int sc_ioctl(int card, scs_ioctl *data)
>                        return status;
>                }
>
> -               dn = kmalloc(SCIOC_DNSIZE, GFP_KERNEL);
> +               dn = kzalloc(SCIOC_DNSIZE, GFP_KERNEL);
>                if (!dn) {
>                        kfree(rcvmsg);
>                        return -ENOMEM;
>                }
> -               strcpy(dn, rcvmsg->msg_data.byte_array);
> +               strlcpy(dn, rcvmsg->msg_data.byte_array, SCIOC_DNSIZE);
>                kfree(rcvmsg);
>
>                /*
> @@ -348,7 +348,7 @@ int sc_ioctl(int card, scs_ioctl *data)
>                pr_debug("%s: SCIOSTAT: ioctl received\n",
>                                sc_adapter[card]->devicename);
>
> -               bi = kmalloc (sizeof(boardInfo), GFP_KERNEL);
> +               bi = kzalloc(sizeof(boardInfo), GFP_KERNEL);
>                if (!bi) {
>                        kfree(rcvmsg);
>                        return -ENOMEM;


-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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