CVE-2023-52933

MEDIUM EPSS 16.4%
Published Mar 27, 20251y ago · Modified Jun 17, 20262w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Mar 27, 2025 1y ago
Last Modified Jun 17, 2026 2w ago

Description

In the Linux kernel, the following vulnerability has been resolved: Squashfs: fix handling and sanity checking of xattr_ids count A Sysbot [1] corrupted filesystem exposes two flaws in the handling and sanity checking of the xattr_ids count in the filesystem. Both of these flaws cause computation overflow due to incorrect typing. In the corrupted filesystem the xattr_ids value is 4294967071, which stored in a signed variable becomes the negative number -225. Flaw 1 (64-bit systems only): The signed integer xattr_ids variable causes sign extension. This causes variable overflow in the SQUASHFS_XATTR_*(A) macros. The variable is first multiplied by sizeof(struct squashfs_xattr_id) where the type of the sizeof operator is "unsigned long". On a 64-bit system this is 64-bits in size, and causes the negative number to be sign extended and widened to 64-bits and then become unsigned. This produces the very large number 18446744073709548016 or 2^64 - 3600. This number when rounded up by SQUASHFS_METADATA_SIZE - 1 (8191 bytes) and divided by SQUASHFS_METADATA_SIZE overflows and produces a length of 0 (stored in len). Flaw 2 (32-bit systems only): On a 32-bit system the integer variable is not widened by the unsigned long type of the sizeof operator (32-bits), and the signedness of the variable has no effect due it always being treated as unsigned. The above corrupted xattr_ids value of 4294967071, when multiplied overflows and produces the number 4294963696 or 2^32 - 3400. This number when rounded up by SQUASHFS_METADATA_SIZE - 1 (8191 bytes) and divided by SQUASHFS_METADATA_SIZE overflows again and produces a length of 0. The effect of the 0 length computation: In conjunction with the corrupted xattr_ids field, the filesystem also has a corrupted xattr_table_start value, where it matches the end of filesystem value of 850. This causes the following sanity check code to fail because the incorrectly computed len of 0 matches the incorrect size of the table reported by the superblock (0 bytes). len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids); indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids); /* * The computed size of the index table (len bytes) should exactly * match the table start and end points */ start = table_start + sizeof(*id_table); end = msblk->bytes_used; if (len != (end - start)) return ERR_PTR(-EINVAL); Changing the xattr_ids variable to be "usigned int" fixes the flaw on a 64-bit system. This relies on the fact the computation is widened by the unsigned long type of the sizeof operator. Casting the variable to u64 in the above macro fixes this flaw on a 32-bit system. It also means 64-bit systems do not implicitly rely on the type of the sizeof operator to widen the computation. [1] https://lore.kernel.org/lkml/000000000000cd44f005f1a0f17f@google.com/

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
16.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-190 Integer Overflow or Wraparound Numeric Error

Affected Products 15

VendorProductVersionRange
linuxlinux_kernel*≥4.4.258  –  <4.5
linuxlinux_kernel*≥4.9.258  –  <4.10
linuxlinux_kernel*≥4.14.222  –  <4.14.306
linuxlinux_kernel*≥4.19.176  –  <4.19.273
linuxlinux_kernel*≥5.4.98  –  <5.4.232
linuxlinux_kernel*≥5.10.16  –  <5.10.168
linuxlinux_kernel*≥5.11.1  –  <5.15.93
linuxlinux_kernel*≥5.16  –  <6.1.11
linuxlinux_kernel5.11any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any

References 7

  • git.kernel.org https://git.kernel.org/stable/c/1369322c1de52c7b9b988b95c9903110a4566778
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5c4d4a83bf1a862d80c1efff1c6e3ce33b501e2e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/7fe583c9bec10cd4b76231c51b37f3e4ca646e01
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/997bed0f3cde78a3e639d624985bf4a95cf767e6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a7da7d01ac5ce9b369a1ac70e1197999cc6c9686
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b38c3e9e0adc01956cc3e5a52e4d3f92f79d88e2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f65c4bbbd682b0877b669828b4e033b8d5d0a2dc
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/1369322c1de52c7b9b988b95c9903110a4566778
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5c4d4a83bf1a862d80c1efff1c6e3ce33b501e2e
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/7fe583c9bec10cd4b76231c51b37f3e4ca646e01
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/997bed0f3cde78a3e639d624985bf4a95cf767e6
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/a7da7d01ac5ce9b369a1ac70e1197999cc6c9686
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b38c3e9e0adc01956cc3e5a52e4d3f92f79d88e2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/f65c4bbbd682b0877b669828b4e033b8d5d0a2dc
    Patch