[PATCH v2 1/2] UBI: Fastmap: free unused fastmap anchor peb during detach

[PATCH v2 1/2] UBI: Fastmap: free unused fastmap anchor peb during detach

[Hou Tao]

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@syzkaller.appspotmail.com
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 drivers/mtd/ubi/fastmap-wl.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)
---
v2: patch splitting as suggested by Sascha

diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index 426820ab9afe..b486250923c5 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -39,6 +39,13 @@ 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
@@ -52,8 +59,7 @@ 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);
 	}
 }
 
@@ -361,6 +367,11 @@ 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]);
-- 
2.22.0


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[PATCH v2 2/2] UBI: fastmap: only produce the initial anchor PEB when fastmap is used

[Hou Tao]

Don't produce the initial anchor PEB when ubi device is read-only
or fastmap is disabled, else the resulting PEB will be unusable
to any volume.

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 drivers/mtd/ubi/wl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index af2fe77eb66f..87ff4e51cb8c 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -1879,7 +1879,8 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 		goto out_free;
 
 #ifdef CONFIG_MTD_UBI_FASTMAP
-	ubi_ensure_anchor_pebs(ubi);
+	if (!ubi->ro_mode && !ubi->fm_disabled)
+		ubi_ensure_anchor_pebs(ubi);
 #endif
 	return 0;
 
-- 
2.22.0


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Re: [PATCH v2 1/2] UBI: Fastmap: free unused fastmap anchor peb during detach

[Richard Weinberger]

On Mon, Feb 10, 2020 at 2:20 PM Hou Tao <houtao1@huawei.com> wrote:
>
> 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@syzkaller.appspotmail.com
> Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
> Signed-off-by: Hou Tao <houtao1@huawei.com>
> ---
>  drivers/mtd/ubi/fastmap-wl.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> ---
> v2: patch splitting as suggested by Sascha

Both applied, thanks a lot!

-- 
Thanks,
//richard

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