* [PATCH] KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332)
@ 2019-12-04 11:20 Paolo Bonzini
2019-12-18 12:24 ` Borislav Petkov
0 siblings, 1 reply; 2+ messages in thread
From: Paolo Bonzini @ 2019-12-04 11:20 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: bp
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);
--
1.8.3.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332)
2019-12-04 11:20 [PATCH] KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332) Paolo Bonzini
@ 2019-12-18 12:24 ` Borislav Petkov
0 siblings, 0 replies; 2+ messages in thread
From: Borislav Petkov @ 2019-12-18 12:24 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm
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!
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-12-04 11:20 [PATCH] KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332) Paolo Bonzini
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