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Mikhail Lobanov d362b21fef KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception 
commit a2620f8932 upstream.

Previously, commit ed129ec905 ("KVM: x86: forcibly leave nested mode
on vCPU reset") addressed an issue where a triple fault occurring in
nested mode could lead to use-after-free scenarios. However, the commit
did not handle the analogous situation for System Management Mode (SMM).

This omission results in triggering a WARN when KVM forces a vCPU INIT
after SHUTDOWN interception while the vCPU is in SMM. This situation was
reprodused using Syzkaller by:

  1) Creating a KVM VM and vCPU
  2) Sending a KVM_SMI ioctl to explicitly enter SMM
  3) Executing invalid instructions causing consecutive exceptions and
     eventually a triple fault

The issue manifests as follows:

  WARNING: CPU: 0 PID: 25506 at arch/x86/kvm/x86.c:12112
  kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112
  Modules linked in:
  CPU: 0 PID: 25506 Comm: syz-executor.0 Not tainted
  6.1.130-syzkaller-00157-g164fe5dde9b6 #0
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
  BIOS 1.12.0-1 04/01/2014
  RIP: 0010:kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112
  Call Trace:
   <TASK>
   shutdown_interception+0x66/0xb0 arch/x86/kvm/svm/svm.c:2136
   svm_invoke_exit_handler+0x110/0x530 arch/x86/kvm/svm/svm.c:3395
   svm_handle_exit+0x424/0x920 arch/x86/kvm/svm/svm.c:3457
   vcpu_enter_guest arch/x86/kvm/x86.c:10959 [inline]
   vcpu_run+0x2c43/0x5a90 arch/x86/kvm/x86.c:11062
   kvm_arch_vcpu_ioctl_run+0x50f/0x1cf0 arch/x86/kvm/x86.c:11283
   kvm_vcpu_ioctl+0x570/0xf00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4122
   vfs_ioctl fs/ioctl.c:51 [inline]
   __do_sys_ioctl fs/ioctl.c:870 [inline]
   __se_sys_ioctl fs/ioctl.c:856 [inline]
   __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:856
   do_syscall_x64 arch/x86/entry/common.c:51 [inline]
   do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
   entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Architecturally, INIT is blocked when the CPU is in SMM, hence KVM's WARN()
in kvm_vcpu_reset() to guard against KVM bugs, e.g. to detect improper
emulation of INIT.  SHUTDOWN on SVM is a weird edge case where KVM needs to
do _something_ sane with the VMCB, since it's technically undefined, and
INIT is the least awful choice given KVM's ABI.

So, double down on stuffing INIT on SHUTDOWN, and force the vCPU out of
SMM to avoid any weirdness (and the WARN).

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: ed129ec905 ("KVM: x86: forcibly leave nested mode on vCPU reset")
Cc: stable@vger.kernel.org
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Mikhail Lobanov <m.lobanov@rosa.ru>
Link: https://lore.kernel.org/r/20250414171207.155121-1-m.lobanov@rosa.ru
[sean: massage changelog, make it clear this isn't architectural behavior]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-05-18 08:24:52 +02:00
arch KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception 2025-05-18 08:24:52 +02:00
block blk-mq: create correct map for fallback case 2025-05-09 09:50:48 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: Kconfig - Select LIB generic option 2025-05-02 07:59:33 +02:00
Documentation bpf: Add namespace to BPF internal symbols 2025-05-02 07:59:04 +02:00
drivers staging: axis-fifo: Correct handling of tx_fifo_depth for size validation 2025-05-18 08:24:51 +02:00
fs mm/userfaultfd: fix uninitialized output field for -EAGAIN race 2025-05-18 08:24:52 +02:00
include mm: vmalloc: support more granular vrealloc() sizing 2025-05-18 08:24:51 +02:00
init rust: clean Rust 1.88.0's unnecessary_transmutes lint 2025-05-18 08:24:51 +02:00
io_uring io_uring: always do atomic put from iowq 2025-05-02 07:59:21 +02:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-05 14:03:02 +01:00
kernel kernel: globalize lookup_or_create_module_kobject() 2025-05-09 09:50:52 +02:00
lib crypto: lib/Kconfig - Hide arch options from user 2025-05-02 07:59:32 +02:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/huge_memory: fix dereferencing invalid pmd migration entry 2025-05-18 08:24:51 +02:00
net net: export a helper for adding up queue stats 2025-05-18 08:24:50 +02:00
rust rust: clean Rust 1.88.0's unnecessary_transmutes lint 2025-05-18 08:24:51 +02:00
samples tracing: Verify event formats that have "%*p.." 2025-05-02 07:58:52 +02:00
scripts objtool: Silence more KCOV warnings, part 2 2025-05-02 07:59:33 +02:00
security landlock: Prepare to add second errata 2025-04-20 10:15:56 +02:00
sound ASoC: simple-card-utils: Fix pointer check in graph_util_parse_link_direction 2025-05-09 09:50:46 +02:00
tools selftests/mm: fix a build failure on powerpc 2025-05-18 08:24:52 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: Allow building irqbypass.ko as as module when kvm.ko is a module 2025-04-20 10:15:54 +02:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-18 08:24:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.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 MAINTAINERS: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
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 MAINTAINERS: add entry for the Rust alloc module 2025-03-13 13:01:47 +01:00
Makefile Linux 6.12.28 2025-05-09 09:50:53 +02:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

README 

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 reStructuredText 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.