Commit ee59ba8b authored by Richard Weinberger's avatar Richard Weinberger
Browse files

UBI: Fix stale pointers in ubi->lookuptbl 



In some error paths the WL sub-system gives up on a PEB
and frees it's ubi_wl_entry struct but does not set
the entry in ubi->lookuptbl to NULL.
Fastmap can stumble over such a stale pointer as it uses
ubi->lookuptbl to find all PEBs.

Fix this by introducing a new helper function which free()s
a WL entry and removes the reference from the lookup table.

Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 24b7a347

drivers/mtd/ubi/wl.c

+31 −16
Original line number Diff line number Diff line
@@ -215,6 +215,20 @@ static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root) 
	rb_insert_color(&e->u.rb, root);

}



/**

 * wl_tree_destroy - destroy a wear-leveling entry.

 * @ubi: UBI device description object

 * @e: the wear-leveling entry to add

 *

 * This function destroys a wear leveling entry and removes

 * the reference from the lookup table.

 */

static void wl_entry_destroy(struct ubi_device *ubi, struct ubi_wl_entry *e)

{

	ubi->lookuptbl[e->pnum] = NULL;

	kmem_cache_free(ubi_wl_entry_slab, e);

}



/**

 * do_work - do one pending work.

 * @ubi: UBI device description object
@@ -1258,7 +1272,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk, 
	err = do_sync_erase(ubi, e1, vol_id, lnum, 0);

	if (err) {

		if (e2)

			kmem_cache_free(ubi_wl_entry_slab, e2);

			wl_entry_destroy(ubi, e2);

		goto out_ro;

	}
@@ -1326,8 +1340,8 @@ out_error: 
	spin_unlock(&ubi->wl_lock);



	ubi_free_vid_hdr(ubi, vid_hdr);

	kmem_cache_free(ubi_wl_entry_slab, e1);

	kmem_cache_free(ubi_wl_entry_slab, e2);

	wl_entry_destroy(ubi, e1);

	wl_entry_destroy(ubi, e2);



out_ro:

	ubi_ro_mode(ubi);
@@ -1469,7 +1483,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, 
	if (shutdown) {

		dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec);

		kfree(wl_wrk);

		kmem_cache_free(ubi_wl_entry_slab, e);

		wl_entry_destroy(ubi, e);

		return 0;

	}
@@ -1515,7 +1529,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, 
		return err;

	}



	kmem_cache_free(ubi_wl_entry_slab, e);

	wl_entry_destroy(ubi, e);

	if (err != -EIO)

		/*

		 * If this is not %-EIO, we have no idea what to do. Scheduling
@@ -1807,9 +1821,10 @@ int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum) 


/**

 * tree_destroy - destroy an RB-tree.

 * @ubi: UBI device description object

 * @root: the root of the tree to destroy

 */

static void tree_destroy(struct rb_root *root)

static void tree_destroy(struct ubi_device *ubi, struct rb_root *root)

{

	struct rb_node *rb;

	struct ubi_wl_entry *e;
@@ -1831,7 +1846,7 @@ static void tree_destroy(struct rb_root *root) 
					rb->rb_right = NULL;

			}



			kmem_cache_free(ubi_wl_entry_slab, e);

			wl_entry_destroy(ubi, e);

		}

	}

}
@@ -1962,7 +1977,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai) 
		ubi_assert(!ubi_is_fm_block(ubi, e->pnum));

		ubi->lookuptbl[e->pnum] = e;

		if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {

			kmem_cache_free(ubi_wl_entry_slab, e);

			wl_entry_destroy(ubi, e);

			goto out_free;

		}
@@ -2056,9 +2071,9 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai) 


out_free:

	shutdown_work(ubi);

	tree_destroy(&ubi->used);

	tree_destroy(&ubi->free);

	tree_destroy(&ubi->scrub);

	tree_destroy(ubi, &ubi->used);

	tree_destroy(ubi, &ubi->free);

	tree_destroy(ubi, &ubi->scrub);

	kfree(ubi->lookuptbl);

	return err;

}
@@ -2075,7 +2090,7 @@ static void protection_queue_destroy(struct ubi_device *ubi) 
	for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {

		list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {

			list_del(&e->u.list);

			kmem_cache_free(ubi_wl_entry_slab, e);

			wl_entry_destroy(ubi, e);

		}

	}

}
@@ -2107,10 +2122,10 @@ void ubi_wl_close(struct ubi_device *ubi) 
	ubi_fastmap_close(ubi);

	shutdown_work(ubi);

	protection_queue_destroy(ubi);

	tree_destroy(&ubi->used);

	tree_destroy(&ubi->erroneous);

	tree_destroy(&ubi->free);

	tree_destroy(&ubi->scrub);

	tree_destroy(ubi, &ubi->used);

	tree_destroy(ubi, &ubi->erroneous);

	tree_destroy(ubi, &ubi->free);

	tree_destroy(ubi, &ubi->scrub);

	kfree(ubi->lookuptbl);

}

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