[PATCH v4 18/25] md/md-llbitmap: clamp state-machine walks to tracked bits

From: Yu Kuai <[email protected]>

llbitmap_state_machine() can be called with an end bit beyond
llbitmap->chunks. In particular, llbitmap_cond_end_sync() passes
sector >> chunkshift, and sector can reach the tracked boundary
exactly.

Clamp the state-machine range to llbitmap->chunks so it cannot walk
past the tracked bitmap.

Signed-off-by: Yu Kuai <[email protected]>
---
 drivers/md/md-llbitmap.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index c3f6e807f739..27418bc001c1 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -1012,7 +1012,10 @@ static enum llbitmap_state llbitmap_state_machine(struct llbitmap *llbitmap,
 		llbitmap_init_state(llbitmap);
 		return BitNone;
 	}
-
+	if (start >= llbitmap->chunks)
+		return BitNone;
+	if (end >= llbitmap->chunks)
+		end = llbitmap->chunks - 1;
 	while (start <= end) {
 		enum llbitmap_state c = llbitmap_read(llbitmap, start);
 
-- 
2.51.0