btrfs: reject free space cache with more entries than pages
In the Linux kernel, the following vulnerability has been resolved: btrfs: reject free space cache with more entries than pages When loading a v1 free space cache, __load_free_space_cache() takes num_entries and num_bitmaps straight from the on-disk btrfs_free_space_header. That header is stored in the tree_root under a key with type 0, which the tree-checker has no case for, so neither count is validated before the load trusts it. The load loops num_entries times and maps the next page whenever the current one runs out, going through io_ctl_check_crc() -> io_ctl_map_page(), which does io_ctl->pages[io_ctl->index++]. But pages[] is allocated in io_ctl_init() from the cache inode's i_size, not from num_entries: num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); io_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS); So if num_entries claims more records than the pages can hold, io_ctl->index runs off the end of pages[]. The write side never hits this because io_ctl_add_entry() and io_ctl_add_bitmap() both stop once io_ctl->index >= io_ctl->num_pages; the read side just never had the same check. To trigger it, take a clean cache (num_entries = here), set num_entries in the header to 0x10000, and fix up the leaf checksum so it still passes the tree-checker. The cache inode has i_size = 65536, so num_pages is 16 and pages[] is a 16-pointer (kmalloc-128) array. The load now tries to read 65536 entries, io_ctl->index walks up to 16, and pages[16] is read past the
CVE-2026-64567
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-2026-64567
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": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "8ded74c654a982dc8581a17b0caa7fcedb20de69",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "c9c38066b6446e83668c041702bb639b0ca49363",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "094734c7aaa2b36751dc32480a680a4952685e78",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "33878ba25e2638bc0c61623d7a05c9ca2b74c039",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "404a0b986e0b6e79738fdf1f0ebbbc43b9acd2a2",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "5e1b2ca6b34939e70fb0785e8222b53cf060016f",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "f9fef131fa3f59b857217f522fa5ea430d1b707c",
"versionType": "git"
},
{
"status": "affected",
"version": "5b0e95bf607ddd59b39f52d3d55e6581c817b530",
"lessThan": "a2d8d5647ed854e38f941741aea45b9eb15a6350",
"versionType": "git"
}
],
"programFiles": [
"fs/btrfs/free-space-cache.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/btrfs/free-space-cache.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-64567
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #41092 · Revision 1
- Added to Heist Feed
- Publisher date