| Date | Mon, 06 May 2013 23:58:21 -0400 | From | Steven Rostedt <> | Subject | [069/126] KVM: Fix bounds checking in ioapic indirect register reads (CVE-2013-1798) |
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3.6.11.3 stable review patch. If anyone has any objections, please let me know.
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From: Andy Honig <ahonig@google.com>
[ Upstream commit a2c118bfab8bc6b8bb213abfc35201e441693d55 ]
If the guest specifies a IOAPIC_REG_SELECT with an invalid value and follows that with a read of the IOAPIC_REG_WINDOW KVM does not properly validate that request. ioapic_read_indirect contains an ASSERT(redir_index < IOAPIC_NUM_PINS), but the ASSERT has no effect in non-debug builds. In recent kernels this allows a guest to cause a kernel oops by reading invalid memory. In older kernels (pre-3.3) this allows a guest to read from large ranges of host memory.
Tested: tested against apic unit tests.
Signed-off-by: Andrew Honig <ahonig@google.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- virt/kvm/ioapic.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index ef61d52..92b1e28 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -73,9 +73,12 @@ static unsigned long ioapic_read_indirect(struct kvm_ioapic *ioapic, u32 redir_index = (ioapic->ioregsel - 0x10) >> 1; u64 redir_content; - ASSERT(redir_index < IOAPIC_NUM_PINS); + if (redir_index < IOAPIC_NUM_PINS) + redir_content = + ioapic->redirtbl[redir_index].bits; + else + redir_content = ~0ULL; - redir_content = ioapic->redirtbl[redir_index].bits; result = (ioapic->ioregsel & 0x1) ? (redir_content >> 32) & 0xffffffff : redir_content & 0xffffffff; -- 1.7.10.4
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