# CVE-2022-49760: mm/hugetlb: fix PTE marker handling in hugetlb_change_protection() > A flaw in Linux kernel hugetlb PTE marker handling allows local attackers to trigger a VM_BUG_ON, causing a denial of service. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 27 Mar 2025 - **Updated:** 15 Oct 2026 - **Also known as:** DEBIAN-CVE-2022-49760, GHSA-jwgp-qffh-vpgp, UBUNTU-CVE-2022-49760 ## What is CVE-2022-49760? CVE-2022-49760 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description 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 that file range, we will run into a VM_BUG_ON: [ 195.039560] page:00000000ba1f2987 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0 [ 195.039565] flags: 0x7ffffc0001000(reserved|node=0|zone=0|lastcpupid=0x1fffff) [ 195.039568] raw: 0007ffffc0001000 ffffe742c0000008 ffffe742c0000008 0000000000000000 [ 195.039569] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 [ 195.039569] page dumped because: VM_BUG_ON_PAGE(compound && !PageHead(page)) [ 195.039573] ------------[ cut here ]------------ [ 195.039574] kernel BUG at mm/rmap.c:1346! [ 195.039579] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 195.039581] CPU: 7 PID: 4777 Comm: qemu-system-x86 Not tainted 6.0.12-200.fc36.x86_64 #1 [ 195.039583] Hardware name: LENOVO 20WNS1F81N/20WNS1F81N, BIOS N35ET50W (1.50 ) 09/15/2022 [ 195.039584] RIP: 0010:page_remove_rmap+0x45b/0x550 [ 195.039588] Code: [...] [ 195.039589] RSP: 0018:ffffbc03c3633ba8 EFLAGS: 00010292 [ 195.039591] RAX: 0000000000000040 RBX: ffffe742c0000000 RCX: 0000000000000000 [ 195.039592] RDX: 0000000000000002 RSI: ffffffff8e7aac1a RDI: 00000000ffffffff [ 195.039592] RBP: 0000000000000001 R08: 0000000000000000 R09: ffffbc03c3633a08 [ 195.039593] R10: 0000000000000003 R11: ffffffff8f146328 R12: ffff9b04c42754b0 [ 195.039594] R13: ffffffff8fcc6328 R14: ffffbc03c3633c80 R15: ffff9b0484ab9100 [ 195.039595] FS: 00007fc7aaf68640(0000) GS:ffff9b0bbf7c0000(0000) knlGS:0000000000000000 [ 195.039596] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 195.039597] CR2: 000055d402c49110 CR3: 0000000159392003 CR4: 0000000000772ee0 [ 195.039598] PKRU: 55555554 [ 195.039599] Call Trace: [ 195.039600] [ 195.039602] __unmap_hugepage_range+0x33b/0x7d0 [ 195.039605] unmap_hugepage_range+0x55/0x70 [ 195.039608] hugetlb_vmdelete_list+0x77/0xa0 [ 195.039611] hugetlbfs_fallocate+0x410/0x550 [ 195.039612] ? _raw_spin_unlock_irqrestore+0x23/0x40 [ 195.039616] vfs_fallocate+0x12e/0x360 [ 195.039618] __x64_sys_fallocate+0x40/0x70 [ 195.039620] do_syscall_64+0x58/0x80 [ 195.039623] ? syscall_exit_to_user_mode+0x17/0x40 [ 195.039624] ? do_syscall_64+0x67/0x80 [ 195.039626] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 195.039628] RIP: 0033:0x7fc7b590651f [ 195.039653] Code: [...] [ 195.039654] RSP: 002b:00007fc7aaf66e70 EFLAGS: 00000293 ORIG_RAX: 000000000000011d [ 195.039655] RAX: ffffffffffffffda RBX: 0000558ef4b7f370 RCX: 00007fc7b590651f ---truncated--- ## Which versions are affected by CVE-2022-49760? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2022-49760? Apply the vendor's patch. ## Is CVE-2022-49760 being exploited? There is no known exploitation of CVE-2022-49760 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2022-49760 and fix it if it is affected. What it is: CVE-2022-49760 is a high-severity memory corruption vulnerability in Linux kernel, published on 27 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2022-49760 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2022-49760/ (Markdown: https://insights.sbomify.com/CVE-2022-49760/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49760 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49760 - OSV: https://osv.dev/vulnerability/CVE-2022-49760 --- From sbomify Insights: https://insights.sbomify.com/CVE-2022-49760/ Summaries are generated and may contain mistakes; the official description above is the record.