Cloudanix VulnDB

CVE-2023-53763

None

CVSS

—

EPSS

0.1%

Published

Dec 8, 2025

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in how Linux handles certain filesystem formats can crash the system when it tries to read specially crafted storage devices.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Denial Of Service
Component
OS kernel
Class
Buffer Overflow
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Out-of-bounds array access in f2fs inline data address calculation during inode recovery, triggered by incorrect extent cache sanity checks on malformed filesystems.

Why it matters to the business

Mounting a crafted f2fs filesystem can cause kernel crashes or undefined behavior on affected Linux systems, leading to denial of service and potential data unavailability.

How an attack unfolds

An attacker supplies a malicious f2fs image that passes initial validation but triggers oversized index values during inode population; the kernel performs an unchecked array access while recovering inline status, resulting in UBSAN-detected out-of-bounds read.

How to fix it

Apply the revert commit that removes the flawed v1 sanity check and ensure the correct v2 fix is present; update to a Linux kernel version containing commit 269d11948100 or later equivalent.

How to confirm the fix worked

Confirm kernel source contains the revert of d48a7b3a72f1 and lacks the oversized index path; test mount operations with f2fs images containing boundary-case inline data sizes.

Typical attack path

  1. Craft a malicious f2fs filesystem image with invalid extent cache metadata
  2. Trigger mount operation on the image via mount system call or automatic mounting
  3. Kernel executes f2fs_fill_super which calls f2fs_iget and do_read_inode
  4. Inline data address calculation performs out-of-bounds access on extent array

How to detect it

Review kernel logs for UBSAN out-of-bounds messages referencing fs/f2fs/f2fs.h or f2fs/inode.c during mount operations; correlate with f2fs superblock parsing failures.

What your security team should do

  • Prioritize kernel updates for systems using f2fs filesystems
  • Disable automatic mounting of untrusted f2fs volumes until patched
  • Monitor for kernel oops or UBSAN reports involving f2fs/inode.c

The record

In the Linux kernel, the following vulnerability has been resolved: Revert "f2fs: fix to do sanity check on extent cache correctly" syzbot reports a f2fs bug as below: UBSAN: array-index-out-of-bounds in fs/f2fs/f2fs.h:3275:19 index 1409 is out of range for type '__le32[923]' (aka 'unsigned int[923]') Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_out_of_bounds+0x11c/0x150 lib/ubsan.c:348 inline_data_addr fs/f2fs/f2fs.h:3275 [inline] __recover_inline_status fs/f2fs/inode.c:113 [inline] do_read_inode fs/f2fs/inode.c:480 [inline] f2fs_iget+0x4730/0x48b0 fs/f2fs/inode.c:604 f2fs_fill_super+0x640e/0x80c0 fs/f2fs/super.c:4601 mount_bdev+0x276/0x3b0 fs/super.c:1391 legacy_get_tree+0xef/0x190 fs/fs_context.c:611 vfs_get_tree+0x8c/0x270 fs/super.c:1519 do_new_mount+0x28f/0xae0 fs/namespace.c:3335 do_mount fs/namespace.c:3675 [inline] __do_sys_mount fs/namespace.c:3884 [inline] __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The issue was bisected to: commit d48a7b3a72f121655d95b5157c32c7d555e44c05 Author: Chao Yu <chao@kernel.org> Date: Mon Jan 9 03:49:20 2023 +0000 f2fs: fix to do sanity check on extent cache correctly The root cause is we applied both v1 and v2 of the patch, v2 is the right fix, so it needs to revert v1 in order to fix reported issue. v1: commit d48a7b3a72f1 ("f2fs: fix to do sanity check on extent cache correctly") https://lore.kernel.org/lkml/20230109034920.492914-1-chao@kernel.org/ v2: commit 269d11948100 ("f2fs: fix to do sanity check on extent cache correctly") https://lore.kernel.org/lkml/20230207134808.1827869-1-chao@kernel.org/

Affected packages

Ecosystem Package Introduced Fixed