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 4.13-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-4.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ac64115a66c18c01745bbd3c47a36b124e5fd8c0 Mon Sep 17 00:00:00 2001 From: Greg Kurz <groug@xxxxxxxx> Date: Thu, 14 Sep 2017 23:56:25 +0200 Subject: KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM From: Greg Kurz <groug@xxxxxxxx> 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@xxxxxxxx> Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -639,8 +639,7 @@ 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@xxxxxxxx are queue-4.13/kvm-ppc-fix-oops-when-checking-kvm_cap_ppc_htm.patch