4.13-stable review patch. If anyone has any objections, please let me know.
------------------
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;