Cloudanix VulnDB

CVE-2023-53846

High · 7.8

CVSS

7.8

EPSS

0.2%

Published

Dec 9, 2025

CISA due date

—

Cloudanix analysis

Next patch cycle SSVC: Track

A flaw in Linux storage code could let an attacker crash the system or potentially take control by manipulating how files are deleted or resized.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Privilege Gain
Component
OS kernel
Class
Use After Free
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Use-after-free in f2fs_truncate_data_blocks_range due to missing sanity check on direct node page during truncate_dnode, allowing out-of-bounds access via inode references after truncation.

Why it matters to the business

Kernel crashes or potential code execution on Linux systems using the f2fs filesystem, risking data loss, service disruption, and requiring urgent patching on affected storage setups.

How an attack unfolds

An attacker triggers the flaw by performing file creation and truncation operations that cause inodeA to reference inodeB; truncation traverses stale node mappings leading to slab-use-after-free.

How to fix it

Update the Linux kernel to the fixed commit af0f716ad3b039cab9d426da63a5ee6c88751185 or later stable versions containing the sanity check and ERROR_INVALID_NODE_REFERENCE handling.

How to confirm the fix worked

Verify kernel version includes the fix commit; mount f2fs and run fsck to confirm absence of ERROR_INVALID_NODE_REFERENCE; test truncation paths with syzkaller-style fuzzing.

Typical attack path

  1. Mount an f2fs filesystem
  2. Create files that establish cross-inode references via node pages
  3. Invoke truncate via setattr or creat system calls
  4. Trigger f2fs_truncate_inode_blocks and traverse invalid node mappings
  5. Cause KASAN-detected use-after-free in data block range processing

How to detect it

Inspect kernel logs for KASAN slab-use-after-free reports mentioning f2fs_truncate_data_blocks_range or truncate_dnode; check f2fs superblock for newly recorded ERROR_INVALID_NODE_REFERENCE errors after fsck runs.

What your security team should do

  • Prioritize kernel upgrade on all f2fs-using systems within standard patch windows
  • Monitor for f2fs superblock error flags indicating invalid node references
  • Restrict untrusted local access until patched

The record

In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to do sanity check on direct node in truncate_dnode() syzbot reports below bug: BUG: KASAN: slab-use-after-free in f2fs_truncate_data_blocks_range+0x122a/0x14c0 fs/f2fs/file.c:574 Read of size 4 at addr ffff88802a25c000 by task syz-executor148/5000 CPU: 1 PID: 5000 Comm: syz-executor148 Not tainted 6.4.0-rc7-syzkaller-00041-ge660abd551f1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351 print_report mm/kasan/report.c:462 [inline] kasan_report+0x11c/0x130 mm/kasan/report.c:572 f2fs_truncate_data_blocks_range+0x122a/0x14c0 fs/f2fs/file.c:574 truncate_dnode+0x229/0x2e0 fs/f2fs/node.c:944 f2fs_truncate_inode_blocks+0x64b/0xde0 fs/f2fs/node.c:1154 f2fs_do_truncate_blocks+0x4ac/0xf30 fs/f2fs/file.c:721 f2fs_truncate_blocks+0x7b/0x300 fs/f2fs/file.c:749 f2fs_truncate.part.0+0x4a5/0x630 fs/f2fs/file.c:799 f2fs_truncate include/linux/fs.h:825 [inline] f2fs_setattr+0x1738/0x2090 fs/f2fs/file.c:1006 notify_change+0xb2c/0x1180 fs/attr.c:483 do_truncate+0x143/0x200 fs/open.c:66 handle_truncate fs/namei.c:3295 [inline] do_open fs/namei.c:3640 [inline] path_openat+0x2083/0x2750 fs/namei.c:3791 do_filp_open+0x1ba/0x410 fs/namei.c:3818 do_sys_openat2+0x16d/0x4c0 fs/open.c:1356 do_sys_open fs/open.c:1372 [inline] __do_sys_creat fs/open.c:1448 [inline] __se_sys_creat fs/open.c:1442 [inline] __x64_sys_creat+0xcd/0x120 fs/open.c:1442 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The root cause is, inodeA references inodeB via inodeB's ino, once inodeA is truncated, it calls truncate_dnode() to truncate data blocks in inodeB's node page, it traverse mapping data from node->i.i_addr[0] to node->i.i_addr[ADDRS_PER_BLOCK() - 1], result in out-of-boundary access. This patch fixes to add sanity check on dnode page in truncate_dnode(), so that, it can help to avoid triggering such issue, and once it encounters such issue, it will record newly introduced ERROR_INVALID_NODE_REFERENCE error into superblock, later fsck can detect such issue and try repairing. Also, it removes f2fs_truncate_data_blocks() for cleanup due to the function has only one caller, and uses f2fs_truncate_data_blocks_range() instead.

Affected packages

Ecosystem Package Introduced Fixed
Linux Kernel 0 6.4.10
Linux Kernel 3.8.0 6.4.10
SUSE:Linux Enterprise High Availability Extension 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Live Patching 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Live Patching 15 SP6 kernel-livepatch-SLE15-SP6_Update_19 0 1-150600.13.3.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-64kb 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-docs 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-obs-build 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-source 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-syms 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server 15 SP6-LTSS kernel-zfcpdump 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-default 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-docs 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-obs-build 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-source 0 6.4.0-150600.23.84.1
SUSE:Linux Enterprise Server for SAP Applications 15 SP6 kernel-syms 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 dtb-aarch64 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-64kb 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-debug 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-default 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-default-base 0 6.4.0-150600.23.84.1.150600.12.38.1
openSUSE:Leap 15.6 kernel-docs 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-kvmsmall 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-obs-build 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-obs-qa 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-source 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-syms 0 6.4.0-150600.23.84.1
openSUSE:Leap 15.6 kernel-zfcpdump 0 6.4.0-150600.23.84.1

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