mtd: speedtest: fix integer overflow

32-bit integers used in 'calc_speed()' may overflow and lead to
incorrect results. Use 64-bit integers instead.

Signed-off-by: David Lambert <dave@lambsys.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/drivers/mtd/tests/mtd_speedtest.c b/drivers/mtd/tests/mtd_speedtest.c
index 3ce6fce75e07..627d4e2466a3 100644
--- a/drivers/mtd/tests/mtd_speedtest.c
+++ b/drivers/mtd/tests/mtd_speedtest.c
@@ -314,16 +314,16 @@ static inline void stop_timing(void)
 
 static long calc_speed(void)
 {
-        long ms, k, speed;
+        uint64_t k;
+        long ms;
 
         ms = (finish.tv_sec - start.tv_sec) * 1000 +
              (finish.tv_usec - start.tv_usec) / 1000;
-        k = goodebcnt * mtd->erasesize / 1024;
-        if (ms)
-                speed = (k * 1000) / ms;
-        else
-                speed = 0;
-        return speed;
+        if (ms == 0)
+                return 0;
+        k = goodebcnt * (mtd->erasesize / 1024) * 1000;
+        do_div(k, ms);
+        return k;
 }
 
 static int scan_for_bad_eraseblocks(void)