[PATCH] xfs: Fix integer overflow in fs/xfs/linux-2.6/xfs_ioctl*.c

[wzt.wzt@gmail.com]

The am_hreq.opcount field in the xfs_attrmulti_by_handle() interface
is not bounded correctly. The opcount is used to determine the size
of the buffer required. The size is bounded, but can overflow and so
the size checks may not be sufficient to catch invalid opcounts.
Fix it by catching opcount values that would cause overflows before
calculating the size.

Signed-off-by: Zhitong Wang <zhitong.wangzt@alibaba-inc.com>

---
 fs/xfs/linux-2.6/xfs_ioctl.c   |    4 ++++
 fs/xfs/linux-2.6/xfs_ioctl32.c |    4 ++++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index a034cf6..b716ec8 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -526,6 +526,10 @@ xfs_attrmulti_by_handle(
 	if (copy_from_user(&am_hreq, arg, sizeof(xfs_fsop_attrmulti_handlereq_t)))
 		return -XFS_ERROR(EFAULT);
 
+	/* overflow check */
+	if (am_hreq.opcount >= INT_MAX / sizeof(xfs_attr_multiop_t))
+		return -E2BIG;
+
 	dentry = xfs_handlereq_to_dentry(parfilp, &am_hreq.hreq);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
diff --git a/fs/xfs/linux-2.6/xfs_ioctl32.c b/fs/xfs/linux-2.6/xfs_ioctl32.c
index be1527b..c9d9d5e 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl32.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl32.c
@@ -419,6 +419,10 @@ xfs_compat_attrmulti_by_handle(
 			   sizeof(compat_xfs_fsop_attrmulti_handlereq_t)))
 		return -XFS_ERROR(EFAULT);
 
+	/* overflow check */
+	if (am_hreq.opcount >= INT_MAX / sizeof(compat_xfs_attr_multiop_t))
+		return -E2BIG;
+
 	dentry = xfs_compat_handlereq_to_dentry(parfilp, &am_hreq.hreq);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
-- 
1.6.5.3