CVE-2024-42233 filemap: replace pte_offset_map() with pte_offset_map_nolock()

2024-08-0715:14:23

Linux

www.cve.org

linux kernel

vulnerability

fix

pte_offset_map

pte_offset_map_nolock

page table .

EPSS

Percentile

9.5%

JSON

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

filemap: replace pte_offset_map() with pte_offset_map_nolock()

The vmf->ptl in filemap_fault_recheck_pte_none() is still set from
handle_pte_fault(). But at the same time, we did a pte_unmap(vmf->pte).
After a pte_unmap(vmf->pte) unmap and rcu_read_unlock(), the page table
may be racily changed and vmf->ptl maybe fails to protect the actual page
table. Fix this by replacing pte_offset_map() with
pte_offset_map_nolock().

As David said, the PTL pointer might be stale so if we continue to use
it infilemap_fault_recheck_pte_none(), it might trigger UAF. Also, if
the PTL fails, the issue fixed by commit 58f327f2ce80 (“filemap: avoid
unnecessary major faults in filemap_fault()”) might reappear.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "mm/filemap.c"
    ],
    "versions": [
      {
        "version": "58f327f2ce80",
        "lessThan": "6a6c2aec1a89",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "58f327f2ce80",
        "lessThan": "24be02a42181",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "mm/filemap.c"
    ],
    "versions": [
      {
        "version": "6.9",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.9",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.10",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]