[PATCH] hpet: disallow zero interrupt frequency

Disallow setting an interrupt frequency of zero (which would result in a
division by zero), and disallow enabling the interrupt when the frequency
hasn't yet been set (which would use an interrupt period of zero).

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index c055bb630ffc..b619ca5eaf8c 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -364,6 +364,9 @@ static int hpet_ioctl_ieon(struct hpet_dev *devp)
         hpet = devp->hd_hpet;
         hpetp = devp->hd_hpets;
 
+        if (!devp->hd_ireqfreq)
+                return -EIO;
+
         v = readq(&timer->hpet_config);
         spin_lock_irq(&hpet_lock);
 
@@ -516,7 +519,7 @@ hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
                         break;
                 }
 
-                if (arg & (arg - 1)) {
+                if (!arg || (arg & (arg - 1))) {
                         err = -EINVAL;
                         break;
                 }