Skip to content
Heist/ feed
Unrated

x86-64: rename misleadingly named '__copy_user_nocache()' function

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: x86-64: rename misleadingly named '__copy_user_nocache()' function This function was a masterclass in bad naming, for various historical reasons. It claimed to be a non-cached user copy. It is literally _neither_ of those things. It's a specialty memory copy routine that uses non-temporal stores for the destination (but not the source), and that does exception handling for both source and destination accesses. Also note that while it works for unaligned targets, any unaligned parts (whether at beginning or end) will not use non-temporal stores, since only words and quadwords can be non-temporal on x86. The exception handling means that it _can_ be used for user space accesses, but not on its own - it needs all the normal "start user space access" logic around it. But typically the user space access would be the source, not the non-temporal destination. That was the original intention of this, where the destination was some fragile persistent memory target that needed non-temporal stores in order to catch machine check exceptions synchronously and deal with them gracefully. Thus that non-descriptive name: one use case was to copy from user space into a non-cached kernel buffer. However, the existing users are a mix of that intended use-case, and a couple of random drivers that just did this as a performance tweak. Some of those random drivers then actively misused the user copying version (with STAC/CLAC and a

Announced Source revision 1
Original source ↗

CVE-2026-43073

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-43073

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "73c2dc2c14d6a2efa5dde469546a907482af07fe",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "14b9194db4a28421a4dbe5d6e519efbaa7c5f3cd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "c6d4e0599e7e73abc04e2488dfeb7940c4039660",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "d993e1723aa2a085aa0d72e70ea889031fc225b4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "efea91ad1729ff1853d7418e4d3bc27d085e72d0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "06917f753547e6bba8a5d17f79971d1c071a70dd",
        "lessThan": "d187a86de793f84766ea40b9ade7ac60aabbb4fe",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "arch/x86/include/asm/uaccess_64.h",
      "arch/x86/lib/copy_user_uncached_64.S",
      "arch/x86/lib/usercopy_64.c",
      "drivers/infiniband/sw/rdmavt/qp.c",
      "drivers/ntb/ntb_transport.c",
      "tools/objtool/check.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.2"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.2",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.83",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.24",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.14",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.1",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "arch/x86/include/asm/uaccess_64.h",
      "arch/x86/lib/copy_user_uncached_64.S",
      "arch/x86/lib/usercopy_64.c",
      "drivers/infiniband/sw/rdmavt/qp.c",
      "drivers/ntb/ntb_transport.c",
      "tools/objtool/check.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-43073

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#46256 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement