exfat: fix valid_size extension over a shared writable mapping
In the Linux kernel, the following vulnerability has been resolved: exfat: fix valid_size extension over a shared writable mapping When a shared writable mapping has its valid_size extended by a buffered write or a page fault, exfat zeroes the page-cache gap below the new valid_size. A store through the mapping can race with this zeroing and be overwritten. Fix this by zeroing the gap lazily. Drop ->map_pages so that every first write fault goes through exfat_page_mkwrite(), which advances valid_size to cover the faulting page. With fault-around enabled, a store could install a writable PTE, skip ->page_mkwrite(), and land past valid_size without advancing it. Extending valid_size one faulting page at a time also leaves never-written pages in a large mapping alone. The gap is filled with block granularity, zeroing only the not-uptodate blocks and preserving blocks that may hold data stored through the mapping. On the buffered-write path the invalidate lock is held and the gap is unmapped before zeroing, so a racing store re-faults and, under the inode lock, completes only after the gap has been zeroed and valid_size covers it.
CVE-2026-92487
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-2026-92487
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": "82a81a7352bcf5f2756ac33d47ee0582737e9a85",
"lessThan": "24f20986b253c3e4eb13ebe3c2007d1d352408a6",
"versionType": "git"
},
{
"status": "affected",
"version": "82a81a7352bcf5f2756ac33d47ee0582737e9a85",
"lessThan": "1135704ed22f54873eb0498a232611d9eca30dd4",
"versionType": "git"
}
],
"programFiles": [
"fs/exfat/exfat_fs.h",
"fs/exfat/file.c",
"fs/exfat/iomap.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/exfat/exfat_fs.h",
"fs/exfat/file.c",
"fs/exfat/iomap.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-92487
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #37723 · Revision 1
- Added to Heist Feed
- Publisher date