mm/hugetlb: fix PTE marker handling in hugetlb_change_protection()
In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix PTE marker handling in hugetlb_change_protection() Patch series "mm/hugetlb: uffd-wp fixes for hugetlb_change_protection()". Playing with virtio-mem and background snapshots (using uffd-wp) on hugetlb in QEMU, I managed to trigger a VM_BUG_ON(). Looking into the details, hugetlb_change_protection() seems to not handle uffd-wp correctly in all cases. Patch #1 fixes my test case. I don't have reproducers for patch #2, as it requires running into migration entries. I did not yet check in detail yet if !hugetlb code requires similar care. This patch (of 2): There are two problematic cases when stumbling over a PTE marker in hugetlb_change_protection(): (1) We protect an uffd-wp PTE marker a second time using uffd-wp: we will end up in the "!huge_pte_none(pte)" case and mess up the PTE marker. (2) We unprotect a uffd-wp PTE marker: we will similarly end up in the "!huge_pte_none(pte)" case even though we cleared the PTE, because the "pte" variable is stale. We'll mess up the PTE marker. For example, if we later stumble over such a "wrongly modified" PTE marker, we'll treat it like a present PTE that maps some garbage page. This can, for example, be triggered by mapping a memfd backed by huge pages, registering uffd-wp, uffd-wp'ing an unmapped page and (a) uffd-wp'ing it a second time; or (b) uffd-unprotecting it; or (c) unregistering uffd-wp. Then, ff we trigger fallocate(FALLOC_FL_PUNCH_HOLE) on t
CVE-2022-49760
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-2022-49760
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": "60dfaad65aa97fb6755b9798a6b3c9e79bcd5930",
"lessThan": "6062c992e912df1eedad52cf64efb3d48e8d35c5",
"versionType": "git"
},
{
"status": "affected",
"version": "60dfaad65aa97fb6755b9798a6b3c9e79bcd5930",
"lessThan": "0e678153f5be7e6c8d28835f5a678618da4b7a9c",
"versionType": "git"
}
],
"programFiles": [
"mm/hugetlb.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.19"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.19",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.8",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"mm/hugetlb.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2022-49760
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #30189 · Revision 1
- Added to Heist Feed
- Publisher date