From: Andrew Price <anprice@redhat.com>
Date: Wed, 6 Nov 2013 16:11:18 +0000 (+0000)
Subject: iowatcher: Add bounds checking in find_step
X-Git-Tag: blktrace-1.1.0~2^2~21
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=173545a6275189f7947e4473cf4dae0de74e1639;p=blktrace.git

iowatcher: Add bounds checking in find_step

Check the value of cur_mini_step is sane before using it as an index to
mini_step array.

Signed-off-by: Andrew Price <anprice@redhat.com>
---

diff --git a/iowatcher/plot.c b/iowatcher/plot.c
index 971a253..d486f29 100644
--- a/iowatcher/plot.c
+++ b/iowatcher/plot.c
@@ -530,10 +530,12 @@ static double find_step(double first, double last, int num_ticks)
 	/* Round to power of 10 */
 	step = exp(floor(log(step) / log10) * log10);
 	/* Scale down step to provide enough ticks */
-	while ((last - first) / (step * mini_step[cur_mini_step]) > num_ticks
-	       && cur_mini_step < TICK_MINI_STEPS)
+	while (cur_mini_step < TICK_MINI_STEPS
+	       && (last - first) / (step * mini_step[cur_mini_step]) > num_ticks)
 		cur_mini_step++;
-	step *= mini_step[cur_mini_step - 1];
+
+	if (cur_mini_step > 0)
+		step *= mini_step[cur_mini_step - 1];
 
 	return step;
 }