| 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-2021-47390: KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() |
| |
| KASAN reports the following issue: |
| |
| BUG: KASAN: stack-out-of-bounds in kvm_make_vcpus_request_mask+0x174/0x440 [kvm] |
| Read of size 8 at addr ffffc9001364f638 by task qemu-kvm/4798 |
| |
| CPU: 0 PID: 4798 Comm: qemu-kvm Tainted: G X --------- --- |
| Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RYM0081C 07/13/2020 |
| Call Trace: |
| dump_stack+0xa5/0xe6 |
| print_address_description.constprop.0+0x18/0x130 |
| ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] |
| __kasan_report.cold+0x7f/0x114 |
| ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] |
| kasan_report+0x38/0x50 |
| kasan_check_range+0xf5/0x1d0 |
| kvm_make_vcpus_request_mask+0x174/0x440 [kvm] |
| kvm_make_scan_ioapic_request_mask+0x84/0xc0 [kvm] |
| ? kvm_arch_exit+0x110/0x110 [kvm] |
| ? sched_clock+0x5/0x10 |
| ioapic_write_indirect+0x59f/0x9e0 [kvm] |
| ? static_obj+0xc0/0xc0 |
| ? __lock_acquired+0x1d2/0x8c0 |
| ? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm] |
| |
| The problem appears to be that 'vcpu_bitmap' is allocated as a single long |
| on stack and it should really be KVM_MAX_VCPUS long. We also seem to clear |
| the lower 16 bits of it with bitmap_zero() for no particular reason (my |
| guess would be that 'bitmap' and 'vcpu_bitmap' variables in |
| kvm_bitmap_or_dest_vcpus() caused the confusion: while the later is indeed |
| 16-bit long, the later should accommodate all possible vCPUs). |
| |
| The Linux kernel CVE team has assigned CVE-2021-47390 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.5 with commit 7ee30bc132c683d06a6d9e360e39e483e3990708 and fixed in 5.10.71 with commit bebabb76ad9acca8858e0371e102fb60d708e25b |
| Issue introduced in 5.5 with commit 7ee30bc132c683d06a6d9e360e39e483e3990708 and fixed in 5.14.10 with commit 99a9e9b80f19fc63be005a33d76211dd23114792 |
| Issue introduced in 5.5 with commit 7ee30bc132c683d06a6d9e360e39e483e3990708 and fixed in 5.15 with commit 2f9b68f57c6278c322793a06063181deded0ad69 |
| |
| 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-2021-47390 |
| 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/ioapic.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/bebabb76ad9acca8858e0371e102fb60d708e25b |
| https://git.kernel.org/stable/c/99a9e9b80f19fc63be005a33d76211dd23114792 |
| https://git.kernel.org/stable/c/2f9b68f57c6278c322793a06063181deded0ad69 |
