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KVM: x86: Fix kernel info-leak in KVM_HC_CLOCK_PAIRING hypercall

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kvm_pv_clock_pairing() allocates local var
"struct kvm_clock_pairing clock_pairing" on stack and initializes
all it's fields besides padding (clock_pairing.pad[]).

Because clock_pairing var is written completely (including padding)
to guest memory, failure to init struct padding results in kernel
info-leak.

Fix the issue by making sure to also init the padding with zeroes.

Fixes: 55dd00a73a ("KVM: x86: add KVM_HC_CLOCK_PAIRING hypercall")
Reported-by: syzbot+a8ef68d71211ba264f56@syzkaller.appspotmail.com
Reviewed-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Liran Alon 2018-11-08 00:43:06 +02:00 committed by Paolo Bonzini
parent 7f9ad1dfa3
commit bcbfbd8ec2
1 changed files with 1 additions and 0 deletions
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1
arch/x86/kvm/x86.c
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@ -6918,6 +6918,7 @@ static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr,
clock_pairing.nsec = ts.tv_nsec;
clock_pairing.tsc = kvm_read_l1_tsc(vcpu, cycle);
clock_pairing.flags = 0;
memset(&clock_pairing.pad, 0, sizeof(clock_pairing.pad));
ret = 0;
if (kvm_write_guest(vcpu->kvm, paddr, &clock_pairing,