2024-09-27 12:39:28
Linux
PUBLISHED
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 isnt 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: