Re: [PATCH] KVM: x86: fix out-of-bounds accesses of rtc_eoi map

[P J P <ppandit@redhat.com>]

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+-- On Wed, 23 Nov 2016, Paolo Bonzini wrote --+
| On 23/11/2016 21:15, Radim Krčmář wrote:
| > KVM was using arrays of size KVM_MAX_VCPUS with vcpu_id, but ID can be
| > bigger that the maximal number of VCPUs, resulting in out-of-bounds
| > access.
| > 
| > Found by syzkaller:
| > 
| >   BUG: KASAN: slab-out-of-bounds in __apic_accept_irq+0xb33/0xb50 at addr [...]
| >   Write of size 1 by task a.out/27101
| >   CPU: 1 PID: 27101 Comm: a.out Not tainted 4.9.0-rc5+ #49
| >   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
| >    [...]
| >   Call Trace:
| >    [...] __apic_accept_irq+0xb33/0xb50 arch/x86/kvm/lapic.c:905
| >    [...] kvm_apic_set_irq+0x10e/0x180 arch/x86/kvm/lapic.c:495
| >    [...] kvm_irq_delivery_to_apic+0x732/0xc10 arch/x86/kvm/irq_comm.c:86
| >    [...] ioapic_service+0x41d/0x760 arch/x86/kvm/ioapic.c:360
| >    [...] ioapic_set_irq+0x275/0x6c0 arch/x86/kvm/ioapic.c:222
| >    [...] kvm_ioapic_inject_all arch/x86/kvm/ioapic.c:235
| >    [...] kvm_set_ioapic+0x223/0x310 arch/x86/kvm/ioapic.c:670
| >    [...] kvm_vm_ioctl_set_irqchip arch/x86/kvm/x86.c:3668
| >    [...] kvm_arch_vm_ioctl+0x1a08/0x23c0 arch/x86/kvm/x86.c:3999
| >    [...] kvm_vm_ioctl+0x1fa/0x1a70 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3099
| 
| Prasad, this needs a CVE.

  Yes, I'm processing it. Thank you so much for CC'ing.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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