CVE-2026-80726

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

KVM: x86/mmu: WARN and clear role.invalid when creating a child shadow page

Explicitly clear role.invalid when deriving a child shadow page's role from

its parent to harden against bugs elsewhere in KVM, as violating KVM's

invariant that invalid pages are NOT on the list of active MMU pages leads

to use-after-free due to _kvmmmupreparezappage() using listadd()

instead of list_move() when processing an invalid shadow page, i.e. makes a

bad situation far worse.

Yell loudly if the parent is invalid, as it means KVM has missed a validity

check, i.e. KVM is attempting to map memory using an invalid/obsolete root,

but continue on as the child is otherwise still a valid shadow page.

  ==================================================================

  BUG: KASAN: slab-use-after-free in _kvmmmugetshadow_page+0x1817/0x1860 [kvm]

  Write of size 8 at addr ff11000153dd1368 by task repro/853

  CPU: 1 UID: 1000 PID: 853 Comm: repro Not tainted 7.2.0-rc2-3aec122bdcaf-next-vm #5 PREEMPT

  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015

  Call Trace:

   <TASK>

   dumpstacklvl+0x4b/0x70

   print_report+0x153/0x49c

   kasan_report+0xbc/0xf0

   _kvmmmugetshadow_page+0x1817/0x1860 [kvm]

   mmuallocroot+0x141/0x320 [kvm]

   kvmmmuload+0x612/0x20f0 [kvm]

   kvmarchvcpuioctlrun+0x3dd5/0x6150 [kvm]

   kvmvcpuioctl+0x5e4/0x10d0 [kvm]

   _x64sys_ioctl+0x131/0x1b0

   dosyscall64+0x67/0x5f0

   entrySYSCALL64afterhwframe+0x4b/0x53

   </TASK>

  Allocated by task 853:

   kasansavestack+0x20/0x40

   kasansavetrack+0x14/0x30

   _kasanslab_alloc+0x5f/0x70

   kmemcachealloc_noprof+0xfe/0x2e0

   _kvmmmutopupmemory_cache+0x135/0x530 [kvm]

   paging64pagefault+0x318/0x1e30 [kvm]

   kvmmmudopagefault+0x21d/0x630 [kvm]

   kvmmmupage_fault+0x18c/0x17b0 [kvm]

   kvmarchvcpuioctlrun+0x1f35/0x6150 [kvm]

   kvmvcpuioctl+0x5e4/0x10d0 [kvm]

   _x64sys_ioctl+0x131/0x1b0

   dosyscall64+0x67/0x5f0

   entrySYSCALL64afterhwframe+0x4b/0x53

  Freed by task 853:

   kasansavestack+0x20/0x40

   kasansavetrack+0x14/0x30

   kasansavefree_info+0x3b/0x60

   _kasanslab_free+0x43/0x70

   kmemcachefree+0xe2/0x400

   kvmmmucommitzappage.part.0+0x1e2/0x310 [kvm]

   kvmmmufree_roots+0x283/0x560 [kvm]

   kvmarchvcpuioctlrun+0x33c8/0x6150 [kvm]

   kvmvcpuioctl+0x5e4/0x10d0 [kvm]

   _x64sys_ioctl+0x131/0x1b0

   dosyscall64+0x67/0x5f0

   entrySYSCALL64afterhwframe+0x4b/0x53