Commit 2d72ab24 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'hyperv-fixes-signed-20230402' of... 

Merge tag 'hyperv-fixes-signed-20230402' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv fixes from Wei Liu:

 - Fix a bug in channel allocation for VMbus (Mohammed Gamal)

 - Do not allow root partition functionality in CVM (Michael Kelley)

* tag 'hyperv-fixes-signed-20230402' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Block root partition functionality in a Confidential VM
  Drivers: vmbus: Check for channel allocation before looking up relids
parents 7e364e56 f8acb24a

arch/x86/kernel/cpu/mshyperv.c

+8 −4
Original line number Diff line number Diff line
@@ -358,12 +358,16 @@ static void __init ms_hyperv_init_platform(void) 
	 * To mirror what Windows does we should extract CPU management

	 * features and use the ReservedIdentityBit to detect if Linux is the

	 * root partition. But that requires negotiating CPU management

	 * interface (a process to be finalized).

	 * interface (a process to be finalized). For now, use the privilege

	 * flag as the indicator for running as root.

	 *

	 * For now, use the privilege flag as the indicator for running as

	 * root.

	 * Hyper-V should never specify running as root and as a Confidential

	 * VM. But to protect against a compromised/malicious Hyper-V trying

	 * to exploit root behavior to expose Confidential VM memory, ignore

	 * the root partition setting if also a Confidential VM.

	 */

	if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {

	if ((ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&

	    !(ms_hyperv.priv_high & HV_ISOLATION)) {

		hv_root_partition = true;

		pr_info("Hyper-V: running as root partition\n");

	}

drivers/hv/connection.c

+4 −0
Original line number Diff line number Diff line
@@ -409,6 +409,10 @@ void vmbus_disconnect(void) 
 */

struct vmbus_channel *relid2channel(u32 relid)

{

	if (vmbus_connection.channels == NULL) {

		pr_warn_once("relid2channel: relid=%d: No channels mapped!\n", relid);

		return NULL;

	}

	if (WARN_ON(relid >= MAX_CHANNEL_RELIDS))

		return NULL;

	return READ_ONCE(vmbus_connection.channels[relid]);