| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21740: KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking |
| |
| When waking a VM's NX huge page recovery thread, ensure the thread is |
| actually alive before trying to wake it. Now that the thread is spawned |
| on-demand during KVM_RUN, a VM without a recovery thread is reachable via |
| the related module params. |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000040 |
| #PF: supervisor read access in kernel mode |
| #PF: error_code(0x0000) - not-present page |
| Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 |
| RIP: 0010:vhost_task_wake+0x5/0x10 |
| Call Trace: |
| <TASK> |
| set_nx_huge_pages+0xcc/0x1e0 [kvm] |
| param_attr_store+0x8a/0xd0 |
| module_attr_store+0x1a/0x30 |
| kernfs_fop_write_iter+0x12f/0x1e0 |
| vfs_write+0x233/0x3e0 |
| ksys_write+0x60/0xd0 |
| do_syscall_64+0x5b/0x160 |
| entry_SYSCALL_64_after_hwframe+0x4b/0x53 |
| RIP: 0033:0x7f3b52710104 |
| </TASK> |
| Modules linked in: kvm_intel kvm |
| CR2: 0000000000000040 |
| |
| The Linux kernel CVE team has assigned CVE-2025-21740 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.14-rc1 with commit 931656b9e2ff7029aee0b36e17780621948a6ac1 and fixed in 6.14-rc2 with commit 43fb96ae78551d7bfa4ecca956b258f085d67c40 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21740 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| arch/x86/kvm/mmu/mmu.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/2b3928b7c896e5a9fb6b1373924adafe8e01a0c6 |
| https://git.kernel.org/stable/c/974f85f1f7eb7dc7fce0988046e06eeccab576a7 |
| https://git.kernel.org/stable/c/43fb96ae78551d7bfa4ecca956b258f085d67c40 |
