CVE-2021-47316 nfsd: fix NULL dereference in nfs3svc_encode_getaclres

2024-05-2114:35:32

Linux

github.com

linux kernel

vulnerability

resolved

nfsd

null dereference

dentry

encoder

6.6 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.7%

JSON

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix NULL dereference in nfs3svc_encode_getaclres

In error cases the dentry may be NULL.

Before 20798dfe249a, the encoder also checked dentry and
d_really_is_positive(dentry), but that looks like overkill to me–zero
status should be enough to guarantee a positive dentry.

This isn’t the first time we’ve seen an error-case NULL dereference
hidden in the initialization of a local variable in an xdr encoder. But
I went back through the other recent rewrites and didn’t spot any
similar bugs.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/nfsd/nfs3acl.c"
    ],
    "versions": [
      {
        "version": "20798dfe249a",
        "lessThan": "650e6f383a6e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "20798dfe249a",
        "lessThan": "ab1016d39cc0",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/nfsd/nfs3acl.c"
    ],
    "versions": [
      {
        "version": "5.13",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.13",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13.4",
        "lessThanOrEqual": "5.13.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]