From: Sage Weil <sage@inktank.com>
Date: Tue, 21 Aug 2012 19:11:51 +0000 (-0700)
Subject: ceph: avoid divide by zero in __validate_layout()
X-Git-Tag: v3.6-rc3~5^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=45f2e081f573526977abfa781a12728f83e9641f;p=platform%2Fupstream%2Fkernel-adaptation-pc.git

ceph: avoid divide by zero in __validate_layout()

If "l->stripe_unit" is zero the the mod on the next line will cause a
divide by zero bug.  This comes from the copy_from_user() in
ceph_ioctl_set_layout_policy().  Passing 0 is valid, though (it means
"do not change") so avoid the % check in that case.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
---

diff --git a/fs/ceph/ioctl.c b/fs/ceph/ioctl.c
index 8e3fb69..1396ceb 100644
--- a/fs/ceph/ioctl.c
+++ b/fs/ceph/ioctl.c
@@ -42,7 +42,8 @@ static long __validate_layout(struct ceph_mds_client *mdsc,
 	/* validate striping parameters */
 	if ((l->object_size & ~PAGE_MASK) ||
 	    (l->stripe_unit & ~PAGE_MASK) ||
-	    ((unsigned)l->object_size % (unsigned)l->stripe_unit))
+	    (l->stripe_unit != 0 &&
+	     ((unsigned)l->object_size % (unsigned)l->stripe_unit)))
 		return -EINVAL;
 
 	/* make sure it's a valid data pool */