Patch "ubi: fastmap: Free unused fastmap anchor peb during detach" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ubi: fastmap: Free unused fastmap anchor peb during detach

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ubi-fastmap-free-unused-fastmap-anchor-peb-during-de.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f9be09791e8ca9deb0f449432e0984fb2135b07e
Author: Hou Tao <houtao1@xxxxxxxxxx>
Date:   Mon Feb 10 21:26:34 2020 +0800

    ubi: fastmap: Free unused fastmap anchor peb during detach
    
    [ Upstream commit c16f39d14a7e0ec59881fbdb22ae494907534384 ]
    
    When CONFIG_MTD_UBI_FASTMAP is enabled, fm_anchor will be assigned
    a free PEB during ubi_wl_init() or ubi_update_fastmap(). However
    if fastmap is not used or disabled on the MTD device, ubi_wl_entry
    related with the PEB will not be freed during detach.
    
    So Fix it by freeing the unused fastmap anchor during detach.
    
    Fixes: f9c34bb52997 ("ubi: Fix producing anchor PEBs")
    Reported-by: syzbot+f317896aae32eb281a58@xxxxxxxxxxxxxxxxxxxxxxxxx
    Reviewed-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
    Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
    Signed-off-by: Richard Weinberger <richard@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index 13efebb400225..e08f6b4637dda 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -48,6 +48,13 @@ static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
 	return victim;
 }
 
+static inline void return_unused_peb(struct ubi_device *ubi,
+				     struct ubi_wl_entry *e)
+{
+	wl_tree_add(e, &ubi->free);
+	ubi->free_count++;
+}
+
 /**
  * return_unused_pool_pebs - returns unused PEB to the free tree.
  * @ubi: UBI device description object
@@ -61,8 +68,7 @@ static void return_unused_pool_pebs(struct ubi_device *ubi,
 
 	for (i = pool->used; i < pool->size; i++) {
 		e = ubi->lookuptbl[pool->pebs[i]];
-		wl_tree_add(e, &ubi->free);
-		ubi->free_count++;
+		return_unused_peb(ubi, e);
 	}
 }
 
@@ -370,6 +376,11 @@ static void ubi_fastmap_close(struct ubi_device *ubi)
 	return_unused_pool_pebs(ubi, &ubi->fm_pool);
 	return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
 
+	if (ubi->fm_anchor) {
+		return_unused_peb(ubi, ubi->fm_anchor);
+		ubi->fm_anchor = NULL;
+	}
+
 	if (ubi->fm) {
 		for (i = 0; i < ubi->fm->used_blocks; i++)
 			kfree(ubi->fm->e[i]);