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    Subject[PATCH 4.14 154/267] KVM: x86: fix out-of-bounds write in KVM_GET_EMULATED_CPUID (CVE-2019-19332)
    Date
    From: Paolo Bonzini <pbonzini@redhat.com>

    commit 433f4ba1904100da65a311033f17a9bf586b287e upstream.

    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>
    Cc: Ben Hutchings <ben@decadent.org.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    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);
    @@ -707,6 +707,9 @@ 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);


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