CVE-2023-52909

MEDIUM EPSS 14.4%
Published Aug 21, 20241y ago · Modified Jun 17, 20261w ago
4.7 CVSS 3.1
Medium
Find Similar
Published Aug 21, 2024 1y ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: fix handling of cached open files in nfsd4_open codepath Commit fb70bf124b05 ("NFSD: Instantiate a struct file when creating a regular NFSv4 file") added the ability to cache an open fd over a compound. There are a couple of problems with the way this currently works: It's racy, as a newly-created nfsd_file can end up with its PENDING bit cleared while the nf is hashed, and the nf_file pointer is still zeroed out. Other tasks can find it in this state and they expect to see a valid nf_file, and can oops if nf_file is NULL. Also, there is no guarantee that we'll end up creating a new nfsd_file if one is already in the hash. If an extant entry is in the hash with a valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with the value of op_file and the old nf_file will leak. Fix both issues by making a new nfsd_file_acquirei_opened variant that takes an optional file pointer. If one is present when this is called, we'll take a new reference to it instead of trying to open the file. If the nfsd_file already has a valid nf_file, we'll just ignore the optional file and pass the nfsd_file back as-is. Also rework the tracepoints a bit to allow for an "opened" variant and don't try to avoid counting acquisitions in the case where we already have a cached open file.

CVSS Details

Base Score
4.7
Exploitability
1.0
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity High
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
14.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 4

VendorProductVersionRange
linuxlinux_kernel*≥5.19  –  <6.1.7
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any
linuxlinux_kernel6.2any

References 4

  • git.kernel.org https://git.kernel.org/stable/c/0b3a551fa58b4da941efeb209b3770868e2eddd7
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/0b778361998d6c6356b8d2fc7ddf025fb3224654
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/45c08a752982116f3287afcd1bd9c50f4fab0c28
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/973acfdfe90c8a4e58ade97ff0653a498531ff2e
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/0b3a551fa58b4da941efeb209b3770868e2eddd7
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/0b778361998d6c6356b8d2fc7ddf025fb3224654
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/45c08a752982116f3287afcd1bd9c50f4fab0c28
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/973acfdfe90c8a4e58ade97ff0653a498531ff2e
    Patch