| 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-2024-50115: KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: nSVM: Ignore nCR3[4:0] when loading PDPTEs from memory |
| |
| Ignore nCR3[4:0] when loading PDPTEs from memory for nested SVM, as bits |
| 4:0 of CR3 are ignored when PAE paging is used, and thus VMRUN doesn't |
| enforce 32-byte alignment of nCR3. |
| |
| In the absolute worst case scenario, failure to ignore bits 4:0 can result |
| in an out-of-bounds read, e.g. if the target page is at the end of a |
| memslot, and the VMM isn't using guard pages. |
| |
| Per the APM: |
| |
| The CR3 register points to the base address of the page-directory-pointer |
| table. The page-directory-pointer table is aligned on a 32-byte boundary, |
| with the low 5 address bits 4:0 assumed to be 0. |
| |
| And the SDM's much more explicit: |
| |
| 4:0 Ignored |
| |
| Note, KVM gets this right when loading PDPTRs, it's only the nSVM flow |
| that is broken. |
| |
| The Linux kernel CVE team has assigned CVE-2024-50115 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 5.10.229 with commit 76ce386feb14ec9a460784fcd495d8432acce7a5 |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 5.15.170 with commit 58cb697d80e669c56197f703e188867c8c54c494 |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 6.1.115 with commit 6876793907cbe19d42e9edc8c3315a21e06c32ae |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 6.6.59 with commit 2c4adc9b192a0815fe58a62bc0709449416cc884 |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 6.11.6 with commit 426682afec71ea3f889b972d038238807b9443e4 |
| Issue introduced in 3.2 with commit e4e517b4be019787ada4cbbce2f04570c21b0cbd and fixed in 6.12 with commit f559b2e9c5c5308850544ab59396b7d53cfc67bd |
| |
| 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-2024-50115 |
| 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/svm/nested.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/76ce386feb14ec9a460784fcd495d8432acce7a5 |
| https://git.kernel.org/stable/c/58cb697d80e669c56197f703e188867c8c54c494 |
| https://git.kernel.org/stable/c/6876793907cbe19d42e9edc8c3315a21e06c32ae |
| https://git.kernel.org/stable/c/2c4adc9b192a0815fe58a62bc0709449416cc884 |
| https://git.kernel.org/stable/c/426682afec71ea3f889b972d038238807b9443e4 |
| https://git.kernel.org/stable/c/f559b2e9c5c5308850544ab59396b7d53cfc67bd |
