[PATCH 1/1] xfs: check for possible overflow in xfs_ioc_trim

[Tomas Racek <tracek@xxxxxxxxxx>]

If range.start argument was between ULLONG_MAX - BBSIZE and ULLONG_MAX,
BTOBB macro resulted in overflow which caused start to be set to 0.
Now, invalid argument error is returned instead.

Signed-off-by: Tomas Racek <tracek@xxxxxxxxxx>
---
 fs/xfs/xfs_discard.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index f9c3fe3..0ef7dd4 100644
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -179,6 +179,10 @@ xfs_ioc_trim(
         * used by the fstrim application.  In the end it really doesn't
         * matter as trimming blocks is an advisory interface.
         */
+
+       if (range.start > ULLONG_MAX - BBSIZE)
+               return -XFS_ERROR(EINVAL);
+
        start = BTOBB(range.start);
        end = start + BTOBBT(range.len) - 1;
        minlen = BTOBB(max_t(u64, granularity, range.minlen));
-- 
1.7.7.6