[PATCH 4.4 126/163] misc: mic/scif: fix wrap around tests

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 7b64dbf849abdd7e769820e25120758f956a7f13 upstream.

Signed integer overflow is undefined.  Also I added a check for
"(offset < 0)" in scif_unregister() because that makes it match the
other conditions and because I didn't want to subtract a negative.

Fixes: ba612aa8b487 ('misc: mic: SCIF memory registration and unregistration')
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/misc/mic/scif/scif_rma.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/misc/mic/scif/scif_rma.c
+++ b/drivers/misc/mic/scif/scif_rma.c
@@ -1511,7 +1511,7 @@ off_t scif_register_pinned_pages(scif_ep
 	if ((map_flags & SCIF_MAP_FIXED) &&
 	    ((ALIGN(offset, PAGE_SIZE) != offset) ||
 	    (offset < 0) ||
-	    (offset + (off_t)len < offset)))
+	    (len > LONG_MAX - offset)))
 		return -EINVAL;
 
 	might_sleep();
@@ -1614,7 +1614,7 @@ off_t scif_register(scif_epd_t epd, void
 	if ((map_flags & SCIF_MAP_FIXED) &&
 	    ((ALIGN(offset, PAGE_SIZE) != offset) ||
 	    (offset < 0) ||
-	    (offset + (off_t)len < offset)))
+	    (len > LONG_MAX - offset)))
 		return -EINVAL;
 
 	/* Unsupported protection requested */
@@ -1732,7 +1732,8 @@ scif_unregister(scif_epd_t epd, off_t of
 
 	/* Offset is not page aligned or offset+len wraps around */
 	if ((ALIGN(offset, PAGE_SIZE) != offset) ||
-	    (offset + (off_t)len < offset))
+	    (offset < 0) ||
+	    (len > LONG_MAX - offset))
 		return -EINVAL;
 
 	err = scif_verify_epd(ep);