[PATCH] ubi: fastmap: Don't produce the initial anchor PEB when fastmap is disabled

[Zhihao Cheng]

Following process triggers a memleak caused by forgetting to release the
initial anchor PEB (CONFIG_MTD_UBI_FASTMAP is disabled):
1. attach -> __erase_worker -> produce the initial anchor PEB
2. detach -> ubi_fastmap_close (Do nothing, it should have released the
   initial anchor PEB)

Don't produce the initial anchor PEB in __erase_worker() when fastmap
is disabled.

Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Fixes: f9c34bb529975fe ("ubi: Fix producing anchor PEBs")
Reported-by: syzbot+d9aab50b1154e3d163f5@xxxxxxxxxxxxxxxxxxxxxxxxx
---
 drivers/mtd/ubi/wl.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 5146cce5fe32..5ebe1084a8e7 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1079,13 +1079,19 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
 	if (!err) {
 		spin_lock(&ubi->wl_lock);
 
-		if (!ubi->fm_anchor && e->pnum < UBI_FM_MAX_START) {
+#ifdef CONFIG_MTD_UBI_FASTMAP
+		if (!ubi->fm_disabled && !ubi->fm_anchor &&
+		    e->pnum < UBI_FM_MAX_START) {
 			ubi->fm_anchor = e;
 			ubi->fm_do_produce_anchor = 0;
 		} else {
 			wl_tree_add(e, &ubi->free);
 			ubi->free_count++;
 		}
+#else
+		wl_tree_add(e, &ubi->free);
+		ubi->free_count++;
+#endif
 
 		spin_unlock(&ubi->wl_lock);
 
-- 
2.25.4