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 <[email protected]>
Signed-off-by: Sage Weil <[email protected]>
Reviewed-by: Alex Elder <[email protected]>
---
 fs/ceph/ioctl.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

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 */
-- 
1.7.9

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