| Message ID | 1575458412-10241-1-git-send-email-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332) | expand |
On Wed, Dec 04, 2019 at 12:20:12PM +0100, Paolo Bonzini wrote: > The bounds check was present in KVM_GET_SUPPORTED_CPUID but not > KVM_GET_EMULATED_CPUID. > > Reported-by: syzbot+e3f4897236c4eeb8af4f@syzkaller.appspotmail.com > Fixes: 84cffe499b94 ("kvm: Emulate MOVBE", 2013-10-29) > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > arch/x86/kvm/cpuid.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 813a4d2e5c0c..cfafa320a8cf 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -504,7 +504,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > > r = -E2BIG; > > - if (*nent >= maxnent) > + if (WARN_ON(*nent >= maxnent)) > goto out; > > do_host_cpuid(entry, function, 0); > @@ -815,6 +815,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, > static int do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 func, > int *nent, int maxnent, unsigned int type) > { > + if (*nent >= maxnent) > + return -E2BIG; > + > if (type == KVM_GET_EMULATED_CPUID) > return __do_cpuid_func_emulated(entry, func, nent, maxnent); > > -- Whoops. ;-\ Thanks for the fix Paolo!
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 813a4d2e5c0c..cfafa320a8cf 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -504,7 +504,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, r = -E2BIG; - if (*nent >= maxnent) + if (WARN_ON(*nent >= maxnent)) goto out; do_host_cpuid(entry, function, 0); @@ -815,6 +815,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function, static int do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 func, int *nent, int maxnent, unsigned int type) { + if (*nent >= maxnent) + return -E2BIG; + if (type == KVM_GET_EMULATED_CPUID) return __do_cpuid_func_emulated(entry, func, nent, maxnent);
The bounds check was present in KVM_GET_SUPPORTED_CPUID but not KVM_GET_EMULATED_CPUID. Reported-by: syzbot+e3f4897236c4eeb8af4f@syzkaller.appspotmail.com Fixes: 84cffe499b94 ("kvm: Emulate MOVBE", 2013-10-29) Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/cpuid.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)