4.19-stable review patch. If anyone has any objections, please let me know.
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From: Liran Alon liran.alon@oracle.com
commit bcbfbd8ec21096027f1ee13ce6c185e8175166f6 upstream.
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: 55dd00a73a51 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/x86.c | 1 + 1 file changed, 1 insertion(+)
--- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -6788,6 +6788,7 @@ static int kvm_pv_clock_pairing(struct k 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,