Patch "KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM" has been added to the 4.9-stable tree

Patch "KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-ppc-fix-oops-when-checking-kvm_cap_ppc_htm.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From ac64115a66c18c01745bbd3c47a36b124e5fd8c0 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Thu, 14 Sep 2017 23:56:25 +0200
Subject: KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM

From: Greg Kurz <groug@kaod.org>

commit ac64115a66c18c01745bbd3c47a36b124e5fd8c0 upstream.

The following program causes a kernel oops:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/kvm.h>

main()
{
    int fd = open("/dev/kvm", O_RDWR);
    ioctl(fd, KVM_CHECK_EXTENSION, KVM_CAP_PPC_HTM);
}

This happens because when using the global KVM fd with
KVM_CHECK_EXTENSION, kvm_vm_ioctl_check_extension() gets
called with a NULL kvm argument, which gets dereferenced
in is_kvmppc_hv_enabled(). Spotted while reading the code.

Let's use the hv_enabled fallback variable, like everywhere
else in this function.

Fixes: 23528bb21ee2 ("KVM: PPC: Introduce KVM_CAP_PPC_HTM")
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/kvm/powerpc.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -601,8 +601,7 @@ int kvm_vm_ioctl_check_extension(struct
 		break;
 #endif
 	case KVM_CAP_PPC_HTM:
-		r = cpu_has_feature(CPU_FTR_TM_COMP) &&
-		    is_kvmppc_hv_enabled(kvm);
+		r = cpu_has_feature(CPU_FTR_TM_COMP) && hv_enabled;
 		break;
 	default:
 		r = 0;


Patches currently in stable-queue which might be from groug@kaod.org are

queue-4.9/kvm-ppc-fix-oops-when-checking-kvm_cap_ppc_htm.patch