linux-cve-announce - CVE-2023-53481: ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed

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Message-ID: <2025100113-CVE-2023-53481-cddb@gregkh>
Date: Wed,  1 Oct 2025 13:42:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53481: ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ubi: ubi_wl_put_peb: Fix infinite loop when wear-leveling work failed

Following process will trigger an infinite loop in ubi_wl_put_peb():

	ubifs_bgt		ubi_bgt
ubifs_leb_unmap
  ubi_leb_unmap
    ubi_eba_unmap_leb
      ubi_wl_put_peb	wear_leveling_worker
                          e1 = rb_entry(rb_first(&ubi->used)
			  e2 = get_peb_for_wl(ubi)
			  ubi_io_read_vid_hdr  // return err (flash fault)
			  out_error:
			    ubi->move_from = ubi->move_to = NULL
			    wl_entry_destroy(ubi, e1)
			      ubi->lookuptbl[e->pnum] = NULL
      retry:
        e = ubi->lookuptbl[pnum];	// return NULL
	if (e == ubi->move_from) {	// NULL == NULL gets true
	  goto retry;			// infinite loop !!!

$ top
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     COMMAND
  7676 root     20   0       0      0      0 R 100.0  0.0  ubifs_bgt0_0

Fix it by:
 1) Letting ubi_wl_put_peb() returns directly if wearl leveling entry has
    been removed from 'ubi->lookuptbl'.
 2) Using 'ubi->wl_lock' protecting wl entry deletion to preventing an
    use-after-free problem for wl entry in ubi_wl_put_peb().

Fetch a reproducer in [Link].

The Linux kernel CVE team has assigned CVE-2023-53481 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 4.14.308 with commit b40d2fbf47af58377e898b5062077a47bb28a132
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 4.19.276 with commit f006f596fe851c3b6aae60b79f89f89f0e515d2f
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 5.4.235 with commit b5be23f6ae610bdb262160a1f294afee6d0e6a69
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 5.10.173 with commit 8a18856e074479bd050b01e688c58defadce7ab0
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 5.15.100 with commit 3afaaf6f5867dc4ad383808d4053f428ec7b867d
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 6.1.18 with commit cc4bc532acda66189bddc03b3fe1ad689d9a48a2
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 6.2.5 with commit 5af1c643184a5d09ff5b3f334077a4d0a163c677
	Issue introduced in 2.6.25 with commit 43f9b25a9cdd7b177f77f026b1461abd1abbd174 and fixed in 6.3 with commit 4d57a7333e26040f2b583983e1970d9d460e56b0

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-53481
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/mtd/ubi/wl.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b40d2fbf47af58377e898b5062077a47bb28a132
	https://git.kernel.org/stable/c/f006f596fe851c3b6aae60b79f89f89f0e515d2f
	https://git.kernel.org/stable/c/b5be23f6ae610bdb262160a1f294afee6d0e6a69
	https://git.kernel.org/stable/c/8a18856e074479bd050b01e688c58defadce7ab0
	https://git.kernel.org/stable/c/3afaaf6f5867dc4ad383808d4053f428ec7b867d
	https://git.kernel.org/stable/c/cc4bc532acda66189bddc03b3fe1ad689d9a48a2
	https://git.kernel.org/stable/c/5af1c643184a5d09ff5b3f334077a4d0a163c677
	https://git.kernel.org/stable/c/4d57a7333e26040f2b583983e1970d9d460e56b0