Subject: Decoding illegal syscall crashes adb (#188)
Index:	bin/adb/opset.c 2.11BSD

Description:
	Asking 'adb' to disassemble a 'trap' instruction which is outside
	the range used for system calls causes 'adb' to core dump.

	Also, when the 'fchdir(2)' syscall was added to the kernel 
	(update #187) the systab[] table in adb did not have a corresponding
	change made.

Repeat-By:
	adb
	adb> 0104666=i
	core dumped

	Use adb(1) to examine a program using the fchdir(2)
	call.  Note the "illegal syscall" message.  

Fix:
	A range check was added - if the syscall number is out of
	bounds then the instruction is decoded using the numeric
	form instead of a symbolic syscall name.

	The change is almost trivial.  An entry is added into the
	syscall table.

	Save the patch below to a file (/tmp/c),  then:

		cd /usr/src/bin/adb
		patch < /tmp/c
		make
		make install
		make clean

========cut here
*** /usr/src/bin/adb/opset.c.old	Wed Jan 12 20:08:48 1994
--- /usr/src/bin/adb/opset.c	Wed May  4 20:56:20 1994
***************
*** 141,147 ****
  	"unlink",
  	"execv",
  	"chdir",
! 	NULL,			/* 13 - old time */
  	"mknod",
  	"chmod",
  	"chown",
--- 141,147 ----
  	"unlink",
  	"execv",
  	"chdir",
! 	"fchdir",
  	"mknod",
  	"chmod",
  	"chown",
***************
*** 290,295 ****
--- 290,297 ----
  	"gldav",
  };
  
+ #define	NUMSYSCALLS	(sizeof (systab) / sizeof (char *))
+ 
  char	*regname[] = { "r0", "r1", "r2", "r3", "r4", "r5", "sp", "pc"};
  
  	u_int	type, space, incp;
***************
*** 346,352 ****
  		break;
  
  	    case SYS:
! 		if (systab[ins])
  			printf("%8t%s", systab[ins]);
  		else
  			printf("%8t%d", ins);
--- 348,354 ----
  		break;
  
  	    case SYS:
! 		if (ins < NUMSYSCALLS && systab[ins])
  			printf("%8t%s", systab[ins]);
  		else
  			printf("%8t%d", ins);