Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.13 07/43] KVM: PPC: Fix oops when checking KVM_CAP_PPC_HTM | Date | Tue, 31 Oct 2017 10:55:27 +0100 |
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4.13-stable review patch. If anyone has any objections, please let me know.
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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 @@ -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;
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