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Blame SOURCES/kvm-i8254-fix-out-of-bounds-memory-access-in-pit_ioport_.patch

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From 5ba6a1889f6da826b7a3b16381977806d8efe553 Mon Sep 17 00:00:00 2001
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From: Petr Matousek <pmatouse@redhat.com>
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Date: Thu, 25 Jun 2015 12:46:37 +0200
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Subject: [PATCH 01/10] i8254: fix out-of-bounds memory access in
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 pit_ioport_read()
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Message-id: <20150625124637.GJ18896@dhcp-25-225.brq.redhat.com>
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Patchwork-id: 66478
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O-Subject: [RHEL-7.2 qemu-kvm PATCH] i8254: fix out-of-bounds memory access in pit_ioport_read()
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Bugzilla: 1229646
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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Upstream: d4862a87e31a51de9eb260f25c9e99a75efe3235
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Due converting PIO to the new memory read/write api we no longer provide
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separate I/O region lenghts for read and write operations. As a result,
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reading from PIT Mode/Command register will end with accessing
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pit->channels with invalid index.
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Fix this by ignoring read from the Mode/Command register.
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This is CVE-2015-3214.
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Reported-by: Matt Tait <matttait@google.com>
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Fixes: 0505bcdec8228d8de39ab1a02644e71999e7c052
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Petr Matousek <pmatouse@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Petr Matousek <pmatouse@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 hw/timer/i8254.c | 6 ++++++
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 1 file changed, 6 insertions(+)
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diff --git a/hw/timer/i8254.c b/hw/timer/i8254.c
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index 20c0c36..64c9f58 100644
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--- a/hw/timer/i8254.c
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+++ b/hw/timer/i8254.c
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@@ -187,6 +187,12 @@ static uint64_t pit_ioport_read(void *opaque, hwaddr addr,
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     PITChannelState *s;
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     addr &= 3;
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+
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+    if (addr == 3) {
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+        /* Mode/Command register is write only, read is ignored */
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+        return 0;
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+    }
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+
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     s = &pit->channels[addr];
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     if (s->status_latched) {
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         s->status_latched = 0;
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-- 
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1.8.3.1
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