CVE-2021-47463

In the Linux kernel, the following vulnerability has been resolved:
mm/secretmem: fix NULL page->mapping dereference in page_is_secretmem()
Check for a NULL page->mapping before dereferencing the mapping in
page_is_secretmem(), as the page’s mapping can be nullified while gup() is
running, e.g. by reclaim or truncation. BUG: kernel NULL pointer
dereference, address: 0000000000000068 #PF: supervisor read access in
kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops:
0000 [#1] PREEMPT SMP NOPTI CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G
W RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0 Code: <48> 81 7a 68 80
08 04 bc 0f 85 21 ff ff 8 89 c7 be RSP: 0018:ffffaa90087679b0 EFLAGS:
00010046 RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900 … CR2:
0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0 Call Trace:
get_user_pages_fast_only+0x13/0x20 hva_to_pfn+0xa9/0x3e0
try_async_pf+0xa1/0x270 direct_page_fault+0x113/0xad0
kvm_mmu_page_fault+0x69/0x680 vmx_handle_exit+0xe1/0x5d0
kvm_arch_vcpu_ioctl_run+0xd81/0x1c70 kvm_vcpu_ioctl+0x267/0x670
__x64_sys_ioctl+0x83/0xa0 do_syscall_64+0x56/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae