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Kazuki Takiguchi 47b0c2e4c2 KVM: x86/mmu: Fix race condition in direct_page_fault
make_mmu_pages_available() must be called with mmu_lock held for write.
However, if the TDP MMU is used, it will be called with mmu_lock held for
read.
This function does nothing unless shadow pages are used, so there is no
race unless nested TDP is used.
Since nested TDP uses shadow pages, old shadow pages may be zapped by this
function even when the TDP MMU is enabled.
Since shadow pages are never allocated by kvm_tdp_mmu_map(), a race
condition can be avoided by not calling make_mmu_pages_available() if the
TDP MMU is currently in use.

I encountered this when repeatedly starting and stopping nested VM.
It can be artificially caused by allocating a large number of nested TDP
SPTEs.

For example, the following BUG and general protection fault are caused in
the host kernel.

pte_list_remove: 00000000cd54fc10 many->many
------------[ cut here ]------------
kernel BUG at arch/x86/kvm/mmu/mmu.c:963!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:pte_list_remove.cold+0x16/0x48 [kvm]
Call Trace:
 <TASK>
 drop_spte+0xe0/0x180 [kvm]
 mmu_page_zap_pte+0x4f/0x140 [kvm]
 __kvm_mmu_prepare_zap_page+0x62/0x3e0 [kvm]
 kvm_mmu_zap_oldest_mmu_pages+0x7d/0xf0 [kvm]
 direct_page_fault+0x3cb/0x9b0 [kvm]
 kvm_tdp_page_fault+0x2c/0xa0 [kvm]
 kvm_mmu_page_fault+0x207/0x930 [kvm]
 npf_interception+0x47/0xb0 [kvm_amd]
 svm_invoke_exit_handler+0x13c/0x1a0 [kvm_amd]
 svm_handle_exit+0xfc/0x2c0 [kvm_amd]
 kvm_arch_vcpu_ioctl_run+0xa79/0x1780 [kvm]
 kvm_vcpu_ioctl+0x29b/0x6f0 [kvm]
 __x64_sys_ioctl+0x95/0xd0
 do_syscall_64+0x5c/0x90

general protection fault, probably for non-canonical address
0xdead000000000122: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:kvm_mmu_commit_zap_page.part.0+0x4b/0xe0 [kvm]
Call Trace:
 <TASK>
 kvm_mmu_zap_oldest_mmu_pages+0xae/0xf0 [kvm]
 direct_page_fault+0x3cb/0x9b0 [kvm]
 kvm_tdp_page_fault+0x2c/0xa0 [kvm]
 kvm_mmu_page_fault+0x207/0x930 [kvm]
 npf_interception+0x47/0xb0 [kvm_amd]

CVE: CVE-2022-45869
Fixes: a2855afc7e ("KVM: x86/mmu: Allow parallel page faults for the TDP MMU")
Signed-off-by: Kazuki Takiguchi <takiguchi.kazuki171@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-23 18:50:08 -05:00
arch KVM: x86/mmu: Fix race condition in direct_page_fault 2022-11-23 18:50:08 -05:00
block block-6.1-2022-11-05 2022-11-05 09:02:28 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation KVM: s390: pv: don't allow userspace to set the clock under PV 2022-11-07 10:14:15 +01:00
drivers cxl fixes for 6.1-rc4 2022-11-06 13:09:52 -08:00
fs Fix a number of bug fixes, including some regressions, the most 2022-11-06 10:30:29 -08:00
include KVM: Obey kvm.halt_poll_ns in VMs not using KVM_CAP_HALT_POLL 2022-11-17 10:50:07 -05:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: unlock if __io_run_local_work locked inside 2022-10-27 09:52:12 -06:00
ipc ipc/msg.c: fix percpu_counter use after free 2022-10-28 13:37:22 -07:00
kernel - Add Cooper Lake's stepping to the PEBS guest/host events isolation 2022-11-06 12:41:32 -08:00
lib Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mmap: fix remap_file_pages() regression 2022-10-28 13:37:23 -07:00
net Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts kconfig: fix segmentation fault in menuconfig search 2022-11-02 17:32:05 +09:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: aoa: Fix I2S device accounting 2022-10-27 08:53:08 +02:00
tools KVM: selftests: add svm part to triple_fault_test 2022-11-17 11:40:00 -05:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Obey kvm.halt_poll_ns in VMs not using KVM_CAP_HALT_POLL 2022-11-17 10:50:07 -05:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap mailmap: update email for Qais Yousef 2022-10-20 21:27:21 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS ARM: SoC fixes for 6.1, part 2 2022-11-04 14:13:12 -07:00
Makefile Linux 6.1-rc4 2022-11-06 15:07:11 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.