Re: [PATCH 3/3] xenoprof fixes: active_domains cleanup

[Markus Armbruster <armbru@redhat.com>]

This is a cleanup the code dealing with /dev/oprofile/active_domains:

* Use parameters instead of global variables to pass domain ids
  around.  Give those globals internal linkage.

* Allocate buffers dynamically to conserve stack space.

* Treat writes with size zero exactly like a write containing no
  domain id.  Before, zero-sized write was ignored, which is not the
  same.

* Parse domain ids as unsigned numbers.  Before, the first one was
  parsed as signed number.

  Because ispunct()-punctuation is ignored between domain ids, signs
  are still silently ignored except for the first number.  Hmm.

* Make parser accept whitespace as domain separator, because that's
  what you get when reading the file.

* EINVAL on domain ids overflowing domid_t.  Before, they were
  silently truncated.

* EINVAL on too many domain ids.  Before, the excess ones were
  silently ignored.

* Reset active domains on failure halfway through setting them.

* Fix potential buffer overflow in adomain_read().  Couldn't really
  happen because buffer was sufficient for current value of
  MAX_OPROF_DOMAINS.

Signed-off-by: Markus Armbruster <armbru@redhat.com>


diff -rup linux-2.6.16.13-xen.patched-2/arch/i386/oprofile/xenoprof.c linux-2.6.16.13-xen.patched-3/arch/i386/oprofile/xenoprof.c
--- linux-2.6.16.13-xen.patched-2/arch/i386/oprofile/xenoprof.c	2006-05-15 10:30:49.000000000 +0200
+++ linux-2.6.16.13-xen.patched-3/arch/i386/oprofile/xenoprof.c	2006-05-15 10:31:23.000000000 +0200
@@ -289,9 +289,13 @@ static int xenoprof_set_active(int * act
 
 	for (i=0; i<adomains; i++) {
 		domid = active_domains[i];
+		if (domid != active_domains[i]) {
+			ret = -EINVAL;
+			goto out;
+		}
 		ret = HYPERVISOR_xenoprof_op(XENOPROF_set_active, &domid);
 		if (ret)
-			return (ret);
+			goto out;
 		if (active_domains[i] == 0)
 			set_dom0 = 1;
 	}
@@ -300,8 +304,11 @@ static int xenoprof_set_active(int * act
 		domid = 0;
 		ret = HYPERVISOR_xenoprof_op(XENOPROF_set_active, &domid);
 	}
-	
-	active_defined = 1;
+
+out:
+	if (ret)
+		HYPERVISOR_xenoprof_op(XENOPROF_reset_active_list, NULL);
+	active_defined = !ret;
 	return ret;
 }
 
diff -rup linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprof.c linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprof.c
--- linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprof.c	2006-05-15 10:31:11.000000000 +0200
+++ linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprof.c	2006-05-15 10:31:44.000000000 +0200
@@ -37,10 +37,7 @@ static DECLARE_MUTEX(start_sem);
  */
 static int timer = 0;
 
-extern unsigned int adomains;
-extern int active_domains[MAX_OPROF_DOMAINS];
-
-int oprofile_set_active(void)
+int oprofile_set_active(int active_domains[], unsigned int adomains)
 {
 	int err;
 
diff -rup linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprof.h linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprof.h
--- linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprof.h	2006-05-15 10:28:11.000000000 +0200
+++ linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprof.h	2006-05-15 10:31:23.000000000 +0200
@@ -36,6 +36,8 @@ void oprofile_timer_init(struct oprofile
 
 int oprofile_set_backtrace(unsigned long depth);
 
-int oprofile_set_active(void);
+#ifdef CONFIG_XEN
+int oprofile_set_active(int active_domains[], unsigned int adomains);
+#endif
  
 #endif /* OPROF_H */
diff -rup linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprofile_files.c linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprofile_files.c
--- linux-2.6.16.13-xen.patched-2/drivers/oprofile/oprofile_files.c	2006-05-15 10:31:11.000000000 +0200
+++ linux-2.6.16.13-xen.patched-3/drivers/oprofile/oprofile_files.c	2006-05-15 10:31:23.000000000 +0200
@@ -126,52 +126,59 @@ static struct file_operations dump_fops 
 
 #define TMPBUFSIZE 512
 
-unsigned int adomains = 0;
-long active_domains[MAX_OPROF_DOMAINS];
+static unsigned int adomains = 0;
+static int active_domains[MAX_OPROF_DOMAINS + 1];
 static DECLARE_MUTEX(adom_sem);
 
 static ssize_t adomain_write(struct file * file, char const __user * buf, 
 			     size_t count, loff_t * offset)
 {
-	char tmpbuf[TMPBUFSIZE];
-	char * startp = tmpbuf;
-	char * endp = tmpbuf;
+	char *tmpbuf;
+	char *startp, *endp;
 	int i;
 	unsigned long val;
 	ssize_t retval = count;
 	
 	if (*offset)
 		return -EINVAL;	
-	if (!count)
-		return 0;
 	if (count > TMPBUFSIZE - 1)
 		return -EINVAL;
 
-	memset(tmpbuf, 0x0, TMPBUFSIZE);
+	if (!(tmpbuf = kmalloc(TMPBUFSIZE, GFP_KERNEL)))
+		return -ENOMEM;
 
-	if (copy_from_user(tmpbuf, buf, count))
+	if (copy_from_user(tmpbuf, buf, count)) {
+		kfree(tmpbuf);
 		return -EFAULT;
-	
-	down(&adom_sem);
+	}
+	tmpbuf[count] = 0;
 
-	for (i = 0; i < MAX_OPROF_DOMAINS; i++)
-		active_domains[i] = -1;
-	adomains = 0;
+	down(&adom_sem);
 
-	while (1) {
-		val = simple_strtol(startp, &endp, 0);
+	startp = tmpbuf;
+	/* Parse one more than MAX_OPROF_DOMAINS, for easy error checking */
+	for (i = 0; i <= MAX_OPROF_DOMAINS; i++) {
+		val = simple_strtoul(startp, &endp, 0);
 		if (endp == startp)
 			break;
-		while (ispunct(*endp))
+		while (ispunct(*endp) || isspace(*endp))
 			endp++;
-		active_domains[adomains++] = val;
-		if (adomains >= MAX_OPROF_DOMAINS)
-			break;
+		active_domains[i] = val;
+		if (active_domains[i] != val)
+			/* Overflow, force error below */
+			i = MAX_OPROF_DOMAINS + 1;
 		startp = endp;
 	}
+	/* Force error on trailing junk */
+	adomains = *startp ? MAX_OPROF_DOMAINS + 1 : i;
 
-	if (oprofile_set_active())
+	kfree(tmpbuf);
+
+	if (adomains > MAX_OPROF_DOMAINS
+	    || oprofile_set_active(active_domains, adomains)) {
+		adomains = 0;
 		retval = -EINVAL;
+	}
 
 	up(&adom_sem);
 	return retval;
@@ -180,22 +187,31 @@ static ssize_t adomain_write(struct file
 static ssize_t adomain_read(struct file * file, char __user * buf, 
 			    size_t count, loff_t * offset)
 {
-	char tmpbuf[TMPBUFSIZE];
-	size_t len = 0;
+	char * tmpbuf;
+	size_t len;
 	int i;
+	ssize_t retval;
+
+	if (!(tmpbuf = kmalloc(TMPBUFSIZE, GFP_KERNEL)))
+		return -ENOMEM;
 
 	down(&adom_sem);
 
-	/* This is all screwed up if we run out of space */
-	for (i = 0; i < adomains; i++) 
-		len += snprintf(tmpbuf + len, TMPBUFSIZE - len, 
-				"%u ", (unsigned int)active_domains[i]);
-	len += snprintf(tmpbuf + len, TMPBUFSIZE - len, "\n");
+	len = 0;
+	for (i = 0; i < adomains; i++)
+		len += snprintf(tmpbuf + len,
+				len < TMPBUFSIZE ? TMPBUFSIZE - len : 0,
+				"%u ", active_domains[i]);
+	WARN_ON(len > TMPBUFSIZE);
+	if (len != 0 && len <= TMPBUFSIZE)
+		tmpbuf[len-1] = '\n';
 
 	up(&adom_sem);
 
-	return simple_read_from_buffer((void __user *)buf, count, 
-				       offset, tmpbuf, len);
+	retval = simple_read_from_buffer(buf, count, offset, tmpbuf, len);
+
+	kfree(tmpbuf);
+	return retval;
 }