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
Reported-by: Dmitry Vyukov <[email protected]>
Cc: [email protected]
Fixes: af1bae5497b9 ("KVM: x86: bump KVM_MAX_VCPU_ID to 1023")
Signed-off-by: Radim Krčmář <[email protected]>
---
Cc: Dmitry Vyukov <[email protected]>
Cc: Steve Rutherford <[email protected]>
---
arch/x86/kvm/ioapic.c | 2 +-
arch/x86/kvm/ioapic.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 1a22de70f7f7..6e219e5c07d2 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -94,7 +94,7 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
{
ioapic->rtc_status.pending_eoi = 0;
- bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPUS);
+ bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID);
}
static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);
diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index 7d2692a49657..1cc6e54436db 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -42,13 +42,13 @@ struct kvm_vcpu;
struct dest_map {
/* vcpu bitmap where IRQ has been sent */
- DECLARE_BITMAP(map, KVM_MAX_VCPUS);
+ DECLARE_BITMAP(map, KVM_MAX_VCPU_ID);
/*
* Vector sent to a given vcpu, only valid when
* the vcpu's bit in map is set
*/
- u8 vectors[KVM_MAX_VCPUS];
+ u8 vectors[KVM_MAX_VCPU_ID];
};
--
2.10.2
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
>
> Reported-by: Dmitry Vyukov <[email protected]>
> Cc: [email protected]
> Fixes: af1bae5497b9 ("KVM: x86: bump KVM_MAX_VCPU_ID to 1023")
> Signed-off-by: Radim Krčmář <[email protected]>
> ---
> Cc: Dmitry Vyukov <[email protected]>
> Cc: Steve Rutherford <[email protected]>
> ---
> arch/x86/kvm/ioapic.c | 2 +-
> arch/x86/kvm/ioapic.h | 4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index 1a22de70f7f7..6e219e5c07d2 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -94,7 +94,7 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic,
> static void rtc_irq_eoi_tracking_reset(struct kvm_ioapic *ioapic)
> {
> ioapic->rtc_status.pending_eoi = 0;
> - bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPUS);
> + bitmap_zero(ioapic->rtc_status.dest_map.map, KVM_MAX_VCPU_ID);
> }
>
> static void kvm_rtc_eoi_tracking_restore_all(struct kvm_ioapic *ioapic);
> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
> index 7d2692a49657..1cc6e54436db 100644
> --- a/arch/x86/kvm/ioapic.h
> +++ b/arch/x86/kvm/ioapic.h
> @@ -42,13 +42,13 @@ struct kvm_vcpu;
>
> struct dest_map {
> /* vcpu bitmap where IRQ has been sent */
> - DECLARE_BITMAP(map, KVM_MAX_VCPUS);
> + DECLARE_BITMAP(map, KVM_MAX_VCPU_ID);
>
> /*
> * Vector sent to a given vcpu, only valid when
> * the vcpu's bit in map is set
> */
> - u8 vectors[KVM_MAX_VCPUS];
> + u8 vectors[KVM_MAX_VCPU_ID];
> };
>
>
>
Reviewed-by: Paolo Bonzini <[email protected]>
Prasad, this needs a CVE.
Paolo
+-- 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
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
Am 23.11.2016 um 21:15 schrieb Radim Krčmář:
> 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
>
> Reported-by: Dmitry Vyukov <[email protected]>
> Cc: [email protected]
> Fixes: af1bae5497b9 ("KVM: x86: bump KVM_MAX_VCPU_ID to 1023")
> Signed-off-by: Radim Krčmář <[email protected]>
> ---
> Cc: Dmitry Vyukov <[email protected]>
> Cc: Steve Rutherford <[email protected]>
> ---
Yes, the array and the bitmap are always accessed using vcpu_id, so this
is correct.
Reviewed-by: David Hildenbrand <[email protected]>
--
David