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Message-ID: <2024092751-CVE-2024-46830-deac@gregkh>
Date: Fri, 27 Sep 2024 14:39:58 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-46830: KVM: x86: Acquire kvm->srcu when handling KVM_SET_VCPU_EVENTS
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Acquire kvm->srcu when handling KVM_SET_VCPU_EVENTS
Grab kvm->srcu when processing KVM_SET_VCPU_EVENTS, as KVM will forcibly
leave nested VMX/SVM if SMM mode is being toggled, and leaving nested VMX
reads guest memory.
Note, kvm_vcpu_ioctl_x86_set_vcpu_events() can also be called from KVM_RUN
via sync_regs(), which already holds SRCU. I.e. trying to precisely use
kvm_vcpu_srcu_read_lock() around the problematic SMM code would cause
problems. Acquiring SRCU isn't all that expensive, so for simplicity,
grab it unconditionally for KVM_SET_VCPU_EVENTS.
=============================
WARNING: suspicious RCU usage
6.10.0-rc7-332d2c1d713e-next-vm #552 Not tainted
-----------------------------
include/linux/kvm_host.h:1027 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by repro/1071:
#0: ffff88811e424430 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x7d/0x970 [kvm]
stack backtrace:
CPU: 15 PID: 1071 Comm: repro Not tainted 6.10.0-rc7-332d2c1d713e-next-vm #552
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl+0x7f/0x90
lockdep_rcu_suspicious+0x13f/0x1a0
kvm_vcpu_gfn_to_memslot+0x168/0x190 [kvm]
kvm_vcpu_read_guest+0x3e/0x90 [kvm]
nested_vmx_load_msr+0x6b/0x1d0 [kvm_intel]
load_vmcs12_host_state+0x432/0xb40 [kvm_intel]
vmx_leave_nested+0x30/0x40 [kvm_intel]
kvm_vcpu_ioctl_x86_set_vcpu_events+0x15d/0x2b0 [kvm]
kvm_arch_vcpu_ioctl+0x1107/0x1750 [kvm]
? mark_held_locks+0x49/0x70
? kvm_vcpu_ioctl+0x7d/0x970 [kvm]
? kvm_vcpu_ioctl+0x497/0x970 [kvm]
kvm_vcpu_ioctl+0x497/0x970 [kvm]
? lock_acquire+0xba/0x2d0
? find_held_lock+0x2b/0x80
? do_user_addr_fault+0x40c/0x6f0
? lock_release+0xb7/0x270
__x64_sys_ioctl+0x82/0xb0
do_syscall_64+0x6c/0x170
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7ff11eb1b539
</TASK>
The Linux kernel CVE team has assigned CVE-2024-46830 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.17 with commit f7e570780efc and fixed in 6.1.110 with commit fa297c33faef
Issue introduced in 5.17 with commit f7e570780efc and fixed in 6.6.51 with commit 939375737b5a
Issue introduced in 5.17 with commit f7e570780efc and fixed in 6.10.10 with commit ecdbe8ac86fb
Issue introduced in 5.17 with commit f7e570780efc and fixed in 6.11 with commit 4bcdd831d9d0
Issue introduced in 5.10.97 with commit 080dbe7e9b86
Issue introduced in 5.15.19 with commit e302786233e6
Issue introduced in 5.16.5 with commit b4c0d89c92e9
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-2024-46830
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/x86.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/fa297c33faefe51e10244e8a378837fca4963228
https://git.kernel.org/stable/c/939375737b5a0b1bf9b1e75129054e11bc9ca65e
https://git.kernel.org/stable/c/ecdbe8ac86fb5538ccc623a41f88ec96c7168ab9
https://git.kernel.org/stable/c/4bcdd831d9d01e0fb64faea50732b59b2ee88da1
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