This is a note to let you know that I've just added the patch titled
ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()
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-fix-uaf-wear-leveling-entry-in-eraseblk_count_se.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 ab1fd03e7b11449cf0c62f91a08faf26c4caae2f
Author: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Date: Sat Jul 30 19:28:37 2022 +0800
ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()
[ Upstream commit a240bc5c43130c6aa50831d7caaa02a1d84e1bce ]
Wear-leveling entry could be freed in error path, which may be accessed
again in eraseblk_count_seq_show(), for example:
__erase_worker eraseblk_count_seq_show
wl = ubi->lookuptbl[*block_number]
if (wl)
wl_entry_destroy
ubi->lookuptbl[e->pnum] = NULL
kmem_cache_free(ubi_wl_entry_slab, e)
erase_count = wl->ec // UAF!
Wear-leveling entry updating/accessing in ubi->lookuptbl should be
protected by ubi->wl_lock, fix it by adding ubi->wl_lock to serialize
wl entry accessing between wl_entry_destroy() and
eraseblk_count_seq_show().
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216305
Fixes: 7bccd12d27b7e3 ("ubi: Add debugfs file for tracking PEB state")
Fixes: 801c135ce73d5d ("UBI: Unsorted Block Images")
Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index ac336164f6253..f1142a2d8bd22 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -865,8 +865,11 @@ 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)
+ if (e2) {
+ spin_lock(&ubi->wl_lock);
wl_entry_destroy(ubi, e2);
+ spin_unlock(&ubi->wl_lock);
+ }
goto out_ro;
}
@@ -1096,14 +1099,18 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
/* Re-schedule the LEB for erasure */
err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false);
if (err1) {
+ spin_lock(&ubi->wl_lock);
wl_entry_destroy(ubi, e);
+ spin_unlock(&ubi->wl_lock);
err = err1;
goto out_ro;
}
return err;
}
+ spin_lock(&ubi->wl_lock);
wl_entry_destroy(ubi, e);
+ spin_unlock(&ubi->wl_lock);
if (err != -EIO)
/*
* If this is not %-EIO, we have no idea what to do. Scheduling
