From 558e10a57db10de355ee97712d2b6df49e9b7849 Mon Sep 17 00:00:00 2001
From: Diego Calleja <diegocg@gmail.com>
Date: Sat, 5 Aug 2006 21:15:58 -0700
Subject: [PATCH] [LAPB]: Fix windowsize check
In bug #6954, Norbert Reinartz reported the following issue:
"Function lapb_setparms() in file net/lapb/lapb_iface.c checks if the given
parameters are valid. If the given window size is in the range of 8 .. 127,
lapb_setparms() fails and returns an error value of LAPB_INVALUE, even if bit
LAPB_EXTENDED in parms->mode is set.
If bit LAPB_EXTENDED in parms->mode is set and the window size is in the range
of 8 .. 127, the first check "(parms->mode & LAPB_EXTENDED)" results true and
the second check "(parms->window < 1 || parms->window > 127)" results false.
Both checks in conjunction result to false, thus the third check "(parms->window
< 1 || parms->window > 7)" is done by fault.
This third check results true, so that we leave lapb_setparms() by 'goto out_put'.
Seems that this bug doesn't cause any problems, because lapb_setparms() isn't
used to change the default values of LAPB. We are using kernel lapb in our
software project and also change the default parameters of lapb, so we found
this bug"
He also pasted a fix, that I've transformated into a patch:
Signed-off-by: Diego Calleja <diegocg@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/lapb/lapb_iface.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/lapb/lapb_iface.c b/net/lapb/lapb_iface.c
index d504eed416f6..7e6bc41eeb21 100644
--- a/net/lapb/lapb_iface.c
+++ b/net/lapb/lapb_iface.c
@@ -238,11 +238,13 @@ int lapb_setparms(struct net_device *dev, struct lapb_parms_struct *parms)
goto out_put;
if (lapb->state == LAPB_STATE_0) {
- if (((parms->mode & LAPB_EXTENDED) &&
- (parms->window < 1 || parms->window > 127)) ||
- (parms->window < 1 || parms->window > 7))
- goto out_put;
-
+ if (parms->mode & LAPB_EXTENDED) {
+ if (parms->window < 1 || parms->window > 127)
+ goto out_put;
+ } else {
+ if (parms->window < 1 || parms->window > 7)
+ goto out_put;
+ }
lapb->mode = parms->mode;
lapb->window = parms->window;
}