>Number:         177
>Category:       port-i386
>Synopsis:       number of ports in com.c has an off-by-one error
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    gnats-admin (GNATS administrator)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Mar 24 20:05:01 1994
>Originator:     bsdealwi@undergrad.math.uwaterloo.ca
>Organization:
"	unorganized"
>Release:        -current to 19th March
>Environment:
	i386-33MHz, i387, for NetBSD/i386
System: NetBSD portia 0.9a PORTIA#4 i386


>Description:
	comopen() checks that the serial unit being accessed is a
	valid number by comparing `unit > NCOM'. `unit' is 0-relative,
	while `NCOM' is 1-relative. Thus the test should be `>='.
>How-To-Repeat:
	
	(x = # configured com-ports. I have 2, so x = 2)
	mknod /dev/test c 8 x
	cat /dev/test
	(kernel will panic)

>Fix:
	
*** /sys/arch/i386/isa/com.c	Thu Mar 24 20:59:27 1994
--- com.c	Thu Mar 24 22:08:23 1994
***************
*** 253,259 ****
  	int s;
  	int error = 0;
   
! 	if (unit > NCOM)
  		return ENXIO;
  	sc = &com_softc[unit];
  	if (!sc->sc_iobase)
--- 253,259 ----
  	int s;
  	int error = 0;
   
! 	if (unit >= NCOM)
  		return ENXIO;
  	sc = &com_softc[unit];
  	if (!sc->sc_iobase)
>Audit-Trail:
>Unformatted:


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