let validaddr send a note and raise an error so resources can be freed 
on waserror() instead of calling pexit. the validaddr call in validname0
was removed, as the first byte should be already validated by the caller
(from syscalls). vmemchr will validate all following pages of the name
if it spans pages. let sysexec validnamedup() a save copy of the file
argument. the rest of the changes are simplifications of the error
handling mostly.

this patch replaces: kernel-sysexec-validnamedup, kernel-sysfile-validaddr,
kernel-segattach-validnamedup and kernel-namec-validaddr. removing the validaddr
calls for the string arguments doesnt work as the user can pass kernel
addresses!

Reference: /n/sources/patch/applied/kernel-validname-error
Date: Sun May  9 19:55:13 CES 2010
Signed-off-by: cinap_lenrek@gmx.de

--- /sys/src/9/port/fault.c	Sun May  9 19:33:05 2010
+++ /sys/src/9/port/fault.c	Sun May  9 19:33:03 2010
@@ -337,8 +337,10 @@
 void
 validaddr(ulong addr, ulong len, int write)
 {
-	if(!okaddr(addr, len, write))
-		pexit("Suicide", 0);
+	if(!okaddr(addr, len, write)){
+		postnote(up, 1, "sys: bad address in syscall", NDebug);
+		error(Ebadarg);
+	}
 }
 
 /*
--- /sys/src/9/port/chan.c	Sun May  9 19:33:13 2010
+++ /sys/src/9/port/chan.c	Sun May  9 19:33:08 2010
@@ -1686,7 +1686,6 @@
 
 	name = aname;
 	if((ulong)name < KZERO){
-		validaddr((ulong)name, 1, 0);
 		if(!dup)
 			print("warning: validname called from %lux with user pointer", pc);
 		ename = vmemchr(name, 0, (1<<16));
--- /sys/src/9/port/auth.c	Sun May  9 19:33:18 2010
+++ /sys/src/9/port/auth.c	Sun May  9 19:33:15 2010
@@ -79,10 +79,10 @@
 
 	ac = mntauth(c, aname);
 	/* at this point ac is responsible for keeping c alive */
-	cclose(c);
 	poperror();	/* c */
-	free(aname);
+	cclose(c);
 	poperror();	/* aname */
+	free(aname);
 
 	if(waserror()){
 		cclose(ac);
--- /sys/src/9/port/sysproc.c	Sun May  9 19:33:24 2010
+++ /sys/src/9/port/sysproc.c	Sun May  9 19:33:20 2010
@@ -222,7 +222,7 @@
 	int i;
 	Chan *tc;
 	char **argv, **argp;
-	char *a, *charp, *args, *file;
+	char *a, *charp, *args, *file, *file0;
 	char *progarg[sizeof(Exec)/2+1], *elem, progelem[64];
 	ulong ssize, spage, nargs, nbytes, n, bssend;
 	int indir;
@@ -233,14 +233,16 @@
 	ulong magic, text, entry, data, bss;
 	Tos *tos;
 
-	validaddr(arg[0], 1, 0);
-	file = (char*)arg[0];
 	indir = 0;
 	elem = nil;
+	validaddr(arg[0], 1, 0);
+	file0 = validnamedup((char*)arg[0], 1);
 	if(waserror()){
+		free(file0);
 		free(elem);
 		nexterror();
 	}
+	file = file0;
 	for(;;){
 		tc = namec(file, Aopen, OEXEC, 0);
 		if(waserror()){
@@ -373,6 +375,7 @@
 		memmove(charp, *argp++, n);
 		charp += n;
 	}
+	free(file0);
 
 	free(up->text);
 	up->text = elem;
--- /sys/src/9/port/sysfile.c	Sun May  9 19:33:31 2010
+++ /sys/src/9/port/sysfile.c	Sun May  9 19:33:27 2010
@@ -266,16 +266,15 @@
 sysopen(ulong *arg)
 {
 	int fd;
-	Chan *c = 0;
+	Chan *c;
 
 	openmode(arg[1]);	/* error check only */
+	validaddr(arg[0], 1, 0);
+	c = namec((char*)arg[0], Aopen, arg[1], 0);
 	if(waserror()){
-		if(c)
-			cclose(c);
+		cclose(c);
 		nexterror();
 	}
-	validaddr(arg[0], 1, 0);
-	c = namec((char*)arg[0], Aopen, arg[1], 0);
 	fd = newfd(c);
 	if(fd < 0)
 		error(Enofd);
@@ -999,9 +998,14 @@
 	if((flag&~MMASK) || (flag&MORDER)==(MBEFORE|MAFTER))
 		error(Ebadarg);
 
-	bogus.flags = flag & MCACHE;
-
 	if(ismount){
+		validaddr((ulong)spec, 1, 0);
+		spec = validnamedup(spec, 1);
+		if(waserror()){
+			free(spec);
+			nexterror();
+		}
+
 		if(up->pgrp->noattach)
 			error(Enoattach);
 
@@ -1017,32 +1021,18 @@
 		if(afd >= 0)
 			ac = fdtochan(afd, ORDWR, 0, 1);
 
+		bogus.flags = flag & MCACHE;
 		bogus.chan = bc;
 		bogus.authchan = ac;
-
-		validaddr((ulong)spec, 1, 0);
 		bogus.spec = spec;
-		if(waserror())
-			error(Ebadspec);
-		spec = validnamedup(spec, 1);
-		poperror();
-		
-		if(waserror()){
-			free(spec);
-			nexterror();
-		}
-
 		ret = devno('M', 0);
 		c0 = devtab[ret]->attach((char*)&bogus);
-
-		poperror();	/* spec */
-		free(spec);
 		poperror();	/* ac bc */
 		if(ac)
 			cclose(ac);
 		cclose(bc);
 	}else{
-		bogus.spec = 0;
+		spec = 0;
 		validaddr((ulong)arg0, 1, 0);
 		c0 = namec(arg0, Abind, 0, 0);
 	}
@@ -1059,15 +1049,17 @@
 		nexterror();
 	}
 
-	ret = cmount(&c0, c1, flag, bogus.spec);
+	ret = cmount(&c0, c1, flag, spec);
 
 	poperror();
 	cclose(c1);
 	poperror();
 	cclose(c0);
-	if(ismount)
+	if(ismount){
 		fdclose(fd, 0);
-
+		poperror();
+		free(spec);
+	}
 	return ret;
 }
 
@@ -1098,35 +1090,28 @@
 
 	validaddr(arg[1], 1, 0);
 	cmount = namec((char *)arg[1], Amount, 0, 0);
+	if(waserror()) {
+		cclose(cmount);
+		if(cmounted)
+			cclose(cmounted);
+		nexterror();
+	}
 
 	if(arg[0]) {
-		if(waserror()) {
-			cclose(cmount);
-			nexterror();
-		}
-		validaddr(arg[0], 1, 0);
 		/*
 		 * This has to be namec(..., Aopen, ...) because
 		 * if arg[0] is something like /srv/cs or /fd/0,
 		 * opening it is the only way to get at the real
 		 * Chan underneath.
 		 */
+		validaddr(arg[0], 1, 0);
 		cmounted = namec((char*)arg[0], Aopen, OREAD, 0);
-		poperror();
 	}
-
-	if(waserror()) {
-		cclose(cmount);
-		if(cmounted)
-			cclose(cmounted);
-		nexterror();
-	}
-
 	cunmount(cmount, cmounted);
+	poperror();
 	cclose(cmount);
 	if(cmounted)
 		cclose(cmounted);
-	poperror();
 	return 0;
 }
 
@@ -1134,16 +1119,15 @@
 syscreate(ulong *arg)
 {
 	int fd;
-	Chan *c = 0;
+	Chan *c;
 
 	openmode(arg[1]&~OEXCL);	/* error check only; OEXCL okay here */
+	validaddr(arg[0], 1, 0);
+	c = namec((char*)arg[0], Acreate, arg[1], arg[2]);
 	if(waserror()) {
-		if(c)
-			cclose(c);
+		cclose(c);
 		nexterror();
 	}
-	validaddr(arg[0], 1, 0);
-	c = namec((char*)arg[0], Acreate, arg[1], arg[2]);
 	fd = newfd(c);
 	if(fd < 0)
 		error(Enofd);