GHSA-6684-J5CX-Q9QW

Vulnerability from github – Published: 2025-09-05 18:31 – Updated: 2026-01-08 18:30
VLAI?
Details

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: 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

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().

Severity ?
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2025-39691"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-09-05T18:15:45Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/buffer: fix use-after-free when call bh_read() helper\n\nThere\u0027s issue as follows:\nBUG: KASAN: stack-out-of-bounds in end_buffer_read_sync+0xe3/0x110\nRead of size 8 at addr ffffc9000168f7f8 by task swapper/3/0\nCPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.16.0-862.14.0.6.x86_64\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996)\nCall Trace:\n \u003cIRQ\u003e\n dump_stack_lvl+0x55/0x70\n print_address_description.constprop.0+0x2c/0x390\n print_report+0xb4/0x270\n kasan_report+0xb8/0xf0\n end_buffer_read_sync+0xe3/0x110\n end_bio_bh_io_sync+0x56/0x80\n blk_update_request+0x30a/0x720\n scsi_end_request+0x51/0x2b0\n scsi_io_completion+0xe3/0x480\n ? scsi_device_unbusy+0x11e/0x160\n blk_complete_reqs+0x7b/0x90\n handle_softirqs+0xef/0x370\n irq_exit_rcu+0xa5/0xd0\n sysvec_apic_timer_interrupt+0x6e/0x90\n \u003c/IRQ\u003e\n\n Above issue happens when do ntfs3 filesystem mount, issue may happens\n as follows:\n           mount                            IRQ\nntfs_fill_super\n  read_cache_page\n    do_read_cache_folio\n      filemap_read_folio\n        mpage_read_folio\n\t do_mpage_readpage\n\t  ntfs_get_block_vbo\n\t   bh_read\n\t     submit_bh\n\t     wait_on_buffer(bh);\n\t                            blk_complete_reqs\n\t\t\t\t     scsi_io_completion\n\t\t\t\t      scsi_end_request\n\t\t\t\t       blk_update_request\n\t\t\t\t        end_bio_bh_io_sync\n\t\t\t\t\t end_buffer_read_sync\n\t\t\t\t\t  __end_buffer_read_notouch\n\t\t\t\t\t   unlock_buffer\n\n            wait_on_buffer(bh);--\u003e return will return to caller\n\n\t\t\t\t\t  put_bh\n\t\t\t\t\t    --\u003e trigger stack-out-of-bounds\nIn the mpage_read_folio() function, the stack variable \u0027map_bh\u0027 is\npassed to ntfs_get_block_vbo(). Once unlock_buffer() unlocks and\nwait_on_buffer() returns to continue processing, the stack variable\nis likely to be reclaimed. Consequently, during the end_buffer_read_sync()\nprocess, calling put_bh() may result in stack overrun.\n\nIf the bh is not allocated on the stack, it belongs to a folio.  Freeing\na buffer head which belongs to a folio is done by drop_buffers() which\nwill fail to free buffers which are still locked.  So it is safe to call\nput_bh() before __end_buffer_read_notouch().",
  "id": "GHSA-6684-j5cx-q9qw",
  "modified": "2026-01-08T18:30:27Z",
  "published": "2025-09-05T18:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39691"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/03b40bf5d0389ca23ae6857ee25789f0e0b47ce8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/042cf48ecf67f72c8b3846c7fac678f472712ff3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3169edb8945c295cf89120fc6b2c35cfe3ad4c9e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/70a09115da586bf662c3bae9c0c4a1b99251fad9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/90b5193edb323fefbee0e4e5bc39ed89dcc37719"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c58c6b532b7b69537cfd9ef701c7e37cdcf79dc4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c5aa6ba1127307ab5dc3773eaf40d73a3423841f"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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