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| author | Andy Honig <ahonig@google.com> | 2013-02-20 14:49:16 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-25 21:23:48 -0700 |
| commit | 17f13c27702d90899081bf70134132ed5f25158e (patch) | |
| tree | 7681aaf5322644c2bd2056b5769beb42968024d9 | |
| parent | df0ed3450c217a1cd571c0d4efa4dc6c458894a9 (diff) | |
| download | lwn-17f13c27702d90899081bf70134132ed5f25158e.tar.gz lwn-17f13c27702d90899081bf70134132ed5f25158e.zip | |
KVM: Fix bounds checking in ioapic indirect register reads (CVE-2013-1798)
commit a2c118bfab8bc6b8bb213abfc35201e441693d55 upstream.
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>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | virt/kvm/ioapic.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 8df1ca104a7f..e99257ccbe8a 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; |