From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 4 Dec 2019 10:28:54 +0100
Subject: KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID
(CVE-2019-19332)
Git-commit: 433f4ba1904100da65a311033f17a9bf586b287e
Patch-mainline: v5.5-rc1
References: CVE-2019-19332 bsc#1158827
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>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/kvm/cpuid.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -404,7 +404,7 @@ static inline int __do_cpuid_ent(struct
r = -E2BIG;
- if (*nent >= maxnent)
+ if (WARN_ON(*nent >= maxnent))
goto out;
do_cpuid_1_ent(entry, function, index);
@@ -706,6 +706,9 @@ out:
static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 func,
u32 idx, int *nent, int maxnent, unsigned int type)
{
+ if (*nent >= maxnent)
+ return -E2BIG;
+
if (type == KVM_GET_EMULATED_CPUID)
return __do_cpuid_ent_emulated(entry, func, idx, nent, maxnent);