[PATCH v4 2/5] accel/amdxdna: check the sync range for overflow on a device BO

amdxdna_drm_sync_bo_ioctl() forms the range for a device BO by adding the
caller's offset and size to the BO address without checking either, while
amdxdna_flush_bo() one call down guards the same arithmetic with
check_add_overflow().

A size that wraps flush_end leaves it below the heap it is clamped
against, so every heap fails the start >= end test, and a sync that asked
for more than the address space holds reports success having flushed
nothing. Reject it instead.

Signed-off-by: Taimuraz Kaitmazov <[email protected]>
---
 drivers/accel/amdxdna/amdxdna_gem.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
index f88b5349cd4b..77a9493cd7ba 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.c
+++ b/drivers/accel/amdxdna/amdxdna_gem.c
@@ -1274,8 +1274,13 @@ int amdxdna_drm_sync_bo_ioctl(struct drm_device *dev,
 		struct amdxdna_gem_obj *heap;
 		unsigned long heap_id;
 		u64 bo_start = amdxdna_gem_dev_addr(abo);
-		u64 flush_start = bo_start + args->offset;
-		u64 flush_end = flush_start + args->size;
+		u64 flush_start, flush_end;
+
+		if (check_add_overflow(bo_start, args->offset, &flush_start) ||
+		    check_add_overflow(flush_start, args->size, &flush_end)) {
+			ret = -EINVAL;
+			goto put_obj;
+		}
 
 		xa_for_each_range(&client->dev_heap_xa, heap_id, heap,
 				  abo->heap_start_id, abo->heap_end_id) {
-- 
2.55.0