FKIE_CVE-2026-64064

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-19 16:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone If a streaming write is made, this will leave the relevant modified folio in a not-uptodate, but dirty state with a netfs_folio struct hung off of folio->private indicating the dirty range. Subsequently truncating the file such that the dirty data in the folio is removed, but the first part of the folio theoretically remains will cause the netfs_folio struct to be discarded... but will leave the dirty flag set. If the folio is then read via mmap(), netfs_read_folio() will see that the page is dirty and jump to netfs_read_gaps() to fill in the missing bits. netfs_read_gaps(), however, expects there to be a netfs_folio struct present and can oops because truncate removed it. Fix this by calling folio_cancel_dirty() in netfs_invalidate_folio() in the event that all the dirty data in the folio is erased (as nfs does). Also add some tracepoints to log modifications to a dirty page. This can be reproduced with something like: dd if=/dev/zero of=/xfstest.test/foo bs=1M count=1 umount /xfstest.test mount /xfstest.test xfs_io -c "w 0xbbbf 0xf96c" \ -c "truncate 0xbbbf" \ -c "mmap -r 0xb000 0x11000" \ -c "mr 0xb000 0x11000" \ /xfstest.test/foo with fscaching disabled (otherwise streaming writes are suppressed) and a change to netfs_perform_write() to disallow streaming writes if the fd is open O_RDWR: if (//(file->f_mode & FMODE_READ) || <--- comment this out netfs_is_cache_enabled(ctx)) { It should be reproducible even without this change, but if prevents the above trivial xfs_io command from reproducing it. Note that the initial dd is important: the file must start out sufficiently large that the zero-point logic doesn't just clear the gaps because it knows there's nothing in the file to read yet. Unmounting and mounting is needed to clear the pagecache (there are other ways to do that that may also work). This was initially reproduced with the generic/522 xfstest on some patches that remove the FMODE_READ restriction.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/156ac2ec2ee77c44c4eb7439d6d165247ba12247
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/31ba145faceb378fa01afcb8349e15ea7d95e542
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/65ae8717abf36202fef02260b64b781d2d44a9bf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fb6ec883b48b8789e5e690dcd440d2db941e840c
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/misc.c",
            "include/trace/events/netfs.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "31ba145faceb378fa01afcb8349e15ea7d95e542",
              "status": "affected",
              "version": "9ebff83e648148b9ece97d4e4890dd84ca54d6ce",
              "versionType": "git"
            },
            {
              "lessThan": "fb6ec883b48b8789e5e690dcd440d2db941e840c",
              "status": "affected",
              "version": "9ebff83e648148b9ece97d4e4890dd84ca54d6ce",
              "versionType": "git"
            },
            {
              "lessThan": "65ae8717abf36202fef02260b64b781d2d44a9bf",
              "status": "affected",
              "version": "9ebff83e648148b9ece97d4e4890dd84ca54d6ce",
              "versionType": "git"
            },
            {
              "lessThan": "156ac2ec2ee77c44c4eb7439d6d165247ba12247",
              "status": "affected",
              "version": "9ebff83e648148b9ece97d4e4890dd84ca54d6ce",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/netfs/misc.c",
            "include/trace/events/netfs.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.92",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone\n\nIf a streaming write is made, this will leave the relevant modified folio\nin a not-uptodate, but dirty state with a netfs_folio struct hung off of\nfolio-\u003eprivate indicating the dirty range.  Subsequently truncating the\nfile such that the dirty data in the folio is removed, but the first part\nof the folio theoretically remains will cause the netfs_folio struct to be\ndiscarded... but will leave the dirty flag set.\n\nIf the folio is then read via mmap(), netfs_read_folio() will see that the\npage is dirty and jump to netfs_read_gaps() to fill in the missing bits.\nnetfs_read_gaps(), however, expects there to be a netfs_folio struct\npresent and can oops because truncate removed it.\n\nFix this by calling folio_cancel_dirty() in netfs_invalidate_folio() in the\nevent that all the dirty data in the folio is erased (as nfs does).\n\nAlso add some tracepoints to log modifications to a dirty page.\n\nThis can be reproduced with something like:\n\n    dd if=/dev/zero of=/xfstest.test/foo bs=1M count=1\n    umount /xfstest.test\n    mount /xfstest.test\n    xfs_io -c \"w 0xbbbf 0xf96c\" \\\n           -c \"truncate 0xbbbf\" \\\n           -c \"mmap -r 0xb000 0x11000\" \\\n           -c \"mr 0xb000 0x11000\" \\\n           /xfstest.test/foo\n\nwith fscaching disabled (otherwise streaming writes are suppressed) and a\nchange to netfs_perform_write() to disallow streaming writes if the fd is\nopen O_RDWR:\n\n\tif (//(file-\u003ef_mode \u0026 FMODE_READ) || \u003c--- comment this out\n\t    netfs_is_cache_enabled(ctx)) {\n\nIt should be reproducible even without this change, but if prevents the\nabove trivial xfs_io command from reproducing it.\n\nNote that the initial dd is important: the file must start out sufficiently\nlarge that the zero-point logic doesn\u0027t just clear the gaps because it\nknows there\u0027s nothing in the file to read yet.  Unmounting and mounting is\nneeded to clear the pagecache (there are other ways to do that that may\nalso work).\n\nThis was initially reproduced with the generic/522 xfstest on some patches\nthat remove the FMODE_READ restriction."
    }
  ],
  "id": "CVE-2026-64064",
  "lastModified": "2026-07-19T16:17:46.937",
  "metrics": {},
  "published": "2026-07-19T16:17:46.937",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/156ac2ec2ee77c44c4eb7439d6d165247ba12247"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/31ba145faceb378fa01afcb8349e15ea7d95e542"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/65ae8717abf36202fef02260b64b781d2d44a9bf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fb6ec883b48b8789e5e690dcd440d2db941e840c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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