U.S. flag   An official website of the United States government
Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock (Dot gov) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Vulnerability Change Records for CVE-2022-49557

Change History

New CVE Received from kernel.org 2/26/2025 2:01:31 AM

Action Type Old Value New Value
Added Description

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

x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave)

Set the starting uABI size of KVM's guest FPU to 'struct kvm_xsave',
i.e. to KVM's historical uABI size.  When saving FPU state for usersapce,
KVM (well, now the FPU) sets the FP+SSE bits in the XSAVE header even if
the host doesn't support XSAVE.  Setting the XSAVE header allows the VM
to be migrated to a host that does support XSAVE without the new host
having to handle FPU state that may or may not be compatible with XSAVE.

Setting the uABI size to the host's default size results in out-of-bounds
writes (setting the FP+SSE bits) and data corruption (that is thankfully
caught by KASAN) when running on hosts without XSAVE, e.g. on Core2 CPUs.

WARN if the default size is larger than KVM's historical uABI size; all
features that can push the FPU size beyond the historical size must be
opt-in.

  ==================================================================
  BUG: KASAN: slab-out-of-bounds in fpu_copy_uabi_to_guest_fpstate+0x86/0x130
  Read of size 8 at addr ffff888011e33a00 by task qemu-build/681
  CPU: 1 PID: 681 Comm: qemu-build Not tainted 5.18.0-rc5-KASAN-amd64 #1
  Hardware name:  /DG35EC, BIOS ECG3510M.86A.0118.2010.0113.1426 01/13/2010
  Call Trace:
   <TASK>
   dump_stack_lvl+0x34/0x45
   print_report.cold+0x45/0x575
   kasan_report+0x9b/0xd0
   fpu_copy_uabi_to_guest_fpstate+0x86/0x130
   kvm_arch_vcpu_ioctl+0x72a/0x1c50 [kvm]
   kvm_vcpu_ioctl+0x47f/0x7b0 [kvm]
   __x64_sys_ioctl+0x5de/0xc90
   do_syscall_64+0x31/0x50
   entry_SYSCALL_64_after_hwframe+0x44/0xae
   </TASK>
  Allocated by task 0:
  (stack is not available)
  The buggy address belongs to the object at ffff888011e33800
   which belongs to the cache kmalloc-512 of size 512
  The buggy address is located 0 bytes to the right of
   512-byte region [ffff888011e33800, ffff888011e33a00)
  The buggy address belongs to the physical page:
  page:0000000089cd4adb refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11e30
  head:0000000089cd4adb order:2 compound_mapcount:0 compound_pincount:0
  flags: 0x4000000000010200(slab|head|zone=1)
  raw: 4000000000010200 dead000000000100 dead000000000122 ffff888001041c80
  raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
  page dumped because: kasan: bad access detected
  Memory state around the buggy address:
   ffff888011e33900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
   ffff888011e33980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  >ffff888011e33a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                     ^
   ffff888011e33a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
   ffff888011e33b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ==================================================================
  Disabling lock debugging due to kernel taint
Added Reference

								
							
							
						
https://git.kernel.org/stable/c/9cf15ebb7dedfe2f27120743b8ea8441c99ac73c
Added Reference

								
							
							
						
https://git.kernel.org/stable/c/c181acbd1a427859d5fda543b95fbae28f7f6068
Added Reference

								
							
							
						
https://git.kernel.org/stable/c/d187ba5312307d51818beafaad87d28a7d939adf