VMCI: check context->notify_page after call to get_user_pages_fast() to avoid GPF

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

VMCI: check context->notify_page after call to get_user_pages_fast() to avoid GPF

The call to get_user_pages_fast() in vmci_host_setup_notify() can return

NULL context->notify_page causing a GPF. To avoid GPF check if

context->notify_page == NULL and return error if so.

general protection fault, probably for non-canonical address

0xe0009d1000000060: 0000 [#1] PREEMPT SMP KASAN NOPTI

KASAN: maybe wild-memory-access in range [0x0005088000000300-

0x0005088000000307]

CPU: 2 PID: 26180 Comm: repro_34802241 Not tainted 6.1.0-rc4 #1

Hardware name: Red Hat KVM, BIOS 1.15.0-2.module+el8.6.0 04/01/2014

RIP: 0010:vmci_ctx_check_signal_notify+0x91/0xe0

Call Trace:

<TASK>

vmci_host_unlocked_ioctl+0x362/0x1f40

__x64_sys_ioctl+0x1a1/0x230

do_syscall_64+0x3a/0x90

entry_SYSCALL_64_after_hwframe+0x63/0xcd