Am 24.11.2011 12:34, schrieb Dan Carpenter:

On Wed, Nov 23, 2011 at 09:25:56AM +0100, walter harms wrote:

quoted

Am 23.11.2011 07:42, schrieb Dan Carpenter:

quoted

These strings come from the user.  We strcpy() them inside
cf_command() so we should check that they are NULL terminated and
return an error if not.

Signed-off-by: Dan Carpenter <redacted>

diff --git a/drivers/isdn/divert/divert_procfs.c b/drivers/isdn/divert/divert_procfs.c
index 33ec9e4..0c16687 100644
--- a/drivers/isdn/divert/divert_procfs.c
+++ b/drivers/isdn/divert/divert_procfs.c

@@ -242,6 +242,10 @@ static int isdn_divert_ioctl_unlocked(struct file *file, uint cmd, ulong arg)
 		case IIOCDOCFINT:
 			if (!divert_if.drv_to_name(dioctl.cf_ctrl.drvid))
 				return (-EINVAL);	/* invalid driver */
+			if (strlen(dioctl.cf_ctrl.msn) >= sizeof(dioctl.cf_ctrl.msn))
+				return -EINVAL;
+			if (strlen(dioctl.cf_ctrl.fwd_nr) >= sizeof(dioctl.cf_ctrl.fwd_nr))
+				return -EINVAL;

forcing the last field to be zero seems more easy.
dioctl.cf_ctrl.fwd_nr[sizeof(dioctl.cf_ctrl.fwd_nr))-1]=0;

That's a valid option to use, but I'd prefer to return an error code
here because that's what we do on the line before.  Passing a too
long string is clearly invalid.

the line before has the same problem, of cause.

So far i see you do not get a string, you get a structure. An it will hard
to validate the element is a useful string. I thing my (sledgehammer) method
is ok here because you make sure that all later calls (strcmp,strcpy) will succeed.
If someone supplies a bad string the later calls will catch by failing to identify
and return a proper code from there (at least i hope so).

re,
 wh