---
id: CVE-2025-39691
title: 'fs/buffer: fix use-after-free when call bh_read() helper'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fs/buffer: fix use-after-free when call bh_read() helper

  There's issue as follows:
  BUG: KASAN: stack-out-of-bounds in end_buffer_read_sync+0xe3/0x110
  Read of size 8 at…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    70a09115da586bf662c3bae9c0c4a1b99251fad9
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    3169edb8945c295cf89120fc6b2c35cfe3ad4c9e
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    03b40bf5d0389ca23ae6857ee25789f0e0b47ce8
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    c5aa6ba1127307ab5dc3773eaf40d73a3423841f
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    042cf48ecf67f72c8b3846c7fac678f472712ff3
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    90b5193edb323fefbee0e4e5bc39ed89dcc37719
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49
  - Linux 2.6.12
published: '2025-09-05'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:42:07.554Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39691'
references:
  - url: 'https://git.kernel.org/stable/c/70a09115da586bf662c3bae9c0c4a1b99251fad9'
  - url: 'https://git.kernel.org/stable/c/3169edb8945c295cf89120fc6b2c35cfe3ad4c9e'
  - url: 'https://git.kernel.org/stable/c/03b40bf5d0389ca23ae6857ee25789f0e0b47ce8'
  - url: 'https://git.kernel.org/stable/c/c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4'
  - url: 'https://git.kernel.org/stable/c/c5aa6ba1127307ab5dc3773eaf40d73a3423841f'
  - url: 'https://git.kernel.org/stable/c/042cf48ecf67f72c8b3846c7fac678f472712ff3'
  - url: 'https://git.kernel.org/stable/c/90b5193edb323fefbee0e4e5bc39ed89dcc37719'
  - url: 'https://git.kernel.org/stable/c/7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49'
tags:
  - cve.org
epss: 0.00179
epssPercentile: 0.06667
ingestedAt: '2026-09-08T15:33:26.997Z'
---

## Overview

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

fs/buffer: fix use-after-free when call bh_read() helper

There's issue as follows:
BUG: KASAN: stack-out-of-bounds in end_buffer_read_sync+0xe3/0x110
Read of size 8 at addr ffffc9000168f7f8 by task swapper/3/0
CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.16.0-862.14.0.6.x86_64
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Call Trace:
 <IRQ>
 dump_stack_lvl+0x55/0x70
 print_address_description.constprop.0+0x2c/0x390
 print_report+0xb4/0x270
 kasan_report+0xb8/0xf0
 end_buffer_read_sync+0xe3/0x110
 end_bio_bh_io_sync+0x56/0x80
 blk_update_request+0x30a/0x720
 scsi_end_request+0x51/0x2b0
 scsi_io_completion+0xe3/0x480
 ? scsi_device_unbusy+0x11e/0x160
 blk_complete_reqs+0x7b/0x90
 handle_softirqs+0xef/0x370
 irq_exit_rcu+0xa5/0xd0
 sysvec_apic_timer_interrupt+0x6e/0x90
 </IRQ>

 Above issue happens when do ntfs3 filesystem mount, issue may happens
 as follows:
           mount                            IRQ
ntfs_fill_super
  read_cache_page
    do_read_cache_folio
      filemap_read_folio
        mpage_read_folio
	 do_mpage_readpage
	  ntfs_get_block_vbo
	   bh_read
	     submit_bh
	     wait_on_buffer(bh);
	                            blk_complete_reqs
				     scsi_io_completion
				      scsi_end_request
				       blk_update_request
				        end_bio_bh_io_sync
					 end_buffer_read_sync
					  __end_buffer_read_notouch
					   unlock_buffer

            wait_on_buffer(bh);--> return will return to caller

					  put_bh
					    --> trigger stack-out-of-bounds
In the mpage_read_folio() function, the stack variable 'map_bh' is
passed to ntfs_get_block_vbo(). Once unlock_buffer() unlocks and
wait_on_buffer() returns to continue processing, the stack variable
is likely to be reclaimed. Consequently, during the end_buffer_read_sync()
process, calling put_bh() may result in stack overrun.

If the bh is not allocated on the stack, it belongs to a folio.  Freeing
a buffer head which belongs to a folio is done by drop_buffers() which
will fail to free buffers which are still locked.  So it is safe to call
put_bh() before __end_buffer_read_notouch().

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 70a09115da586bf662c3bae9c0c4a1b99251fad9`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 3169edb8945c295cf89120fc6b2c35cfe3ad4c9e`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 03b40bf5d0389ca23ae6857ee25789f0e0b47ce8`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < c5aa6ba1127307ab5dc3773eaf40d73a3423841f`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 042cf48ecf67f72c8b3846c7fac678f472712ff3`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 90b5193edb323fefbee0e4e5bc39ed89dcc37719`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49`
- `Linux 2.6.12`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.