CVE-2026-43214

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Add SRCU protection for reading PDPTRs in _getsregs2()

Add SRCU read-side protection when reading PDPTR registers in _getsregs2().

Reading PDPTRs may trigger access to guest memory: kvmpdptrread() -> svmcachereg() -> loadpdptrs() -> kvmvcpureadguestpage() -> kvmvcpugfnto_memslot()

kvmvcpugfntomemslot() dereferences memslots via __kvmmemslots(), which uses srcudereferencecheck() and requires either kvm->srcu or kvm->slotslock to be held. Currently only vcpu->mutex is held, triggering lockdep warning:

============================= WARNING: suspicious RCU usage in kvmvcpugfntomemslot 6.12.59+ #3 Not tainted

include/linux/kvmhost.h:1062 suspicious rcudereference_check() usage!

other info that might help us debug this:

rcuscheduleractive = 2, debuglocks = 1 1 lock held by syz.5.1717/15100: #0: ff1100002f4b00b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvmvcpu_ioctl+0x1d5/0x1590

Call Trace: <TASK> __dumpstack lib/dumpstack.c:94 [inline] dump_stacklvl+0xf0/0x120 lib/dumpstack.c:120 lockdeprcususpicious+0x1e3/0x270 kernel/locking/lockdep.c:6824 __kvmmemslots include/linux/kvmhost.h:1062 [inline] __kvmmemslots include/linux/kvmhost.h:1059 [inline] kvmvcpumemslots include/linux/kvmhost.h:1076 [inline] kvmvcpugfntomemslot+0x518/0x5e0 virt/kvm/kvmmain.c:2617 kvmvcpureadguestpage+0x27/0x50 virt/kvm/kvmmain.c:3302 loadpdptrs+0xff/0x4b0 arch/x86/kvm/x86.c:1065 svmcachereg+0x1c9/0x230 arch/x86/kvm/svm/svm.c:1688 kvmpdptrread arch/x86/kvm/kvmcacheregs.h:141 [inline] __getsregs2 arch/x86/kvm/x86.c:11784 [inline] kvmarchvcpuioctl+0x3e20/0x4aa0 arch/x86/kvm/x86.c:6279 kvmvcpuioctl+0x856/0x1590 virt/kvm/kvmmain.c:4663 vfsioctl fs/ioctl.c:51 [inline] __dosysioctl fs/ioctl.c:907 [inline] __sesysioctl fs/ioctl.c:893 [inline] __x64sysioctl+0x18b/0x210 fs/ioctl.c:893 dosyscallx64 arch/x86/entry/common.c:52 [inline] dosyscall64+0xbd/0x1d0 arch/x86/entry/common.c:83 entrySYSCALL64afterhwframe+0x77/0x7f

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