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From 3150a448434da70b69e0b96d71223161a78d536f Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:20 +0100
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Subject: [PATCH 13/49] bochs: Check extent_size header field (CVE-2014-0142)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-14-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 13/48] bochs: Check extent_size header field (CVE-2014-0142)
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Bugzilla: 1079315
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RH-Acked-by: Jeff Cody <jcody@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1079315
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Upstream status: Embargoed
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This fixes two possible division by zero crashes: In bochs_open() and in
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seek_to_sector().
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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 block/bochs.c              |    8 ++++++++
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 tests/qemu-iotests/078     |   13 +++++++++++++
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 tests/qemu-iotests/078.out |    8 ++++++++
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 3 files changed, 29 insertions(+), 0 deletions(-)
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diff --git a/block/bochs.c b/block/bochs.c
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index d1b1a2c..0ec980a 100644
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--- a/block/bochs.c
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+++ b/block/bochs.c
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@@ -147,6 +147,14 @@ static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
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     s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
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     s->extent_size = le32_to_cpu(bochs.extent);
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+    if (s->extent_size == 0) {
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+        error_setg(errp, "Extent size may not be zero");
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+        return -EINVAL;
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+    } else if (s->extent_size > 0x800000) {
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+        error_setg(errp, "Extent size %" PRIu32 " is too large",
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+                   s->extent_size);
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+        return -EINVAL;
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+    }
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     if (s->catalog_size < bs->total_sectors / s->extent_size) {
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         error_setg(errp, "Catalog size is too small for this disk size");
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diff --git a/tests/qemu-iotests/078 b/tests/qemu-iotests/078
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index 902ef0f..872e734 100755
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--- a/tests/qemu-iotests/078
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+++ b/tests/qemu-iotests/078
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@@ -43,6 +43,7 @@ _supported_proto generic
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 _supported_os Linux
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 catalog_size_offset=$((0x48))
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+extent_size_offset=$((0x50))
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 disk_size_offset=$((0x58))
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 echo
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@@ -68,6 +69,18 @@ _use_sample_img empty.bochs.bz2
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 poke_file "$TEST_IMG" "$disk_size_offset" "\x00\xc0\x0f\x00\x00\x00\x00\x7f"
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 { $QEMU_IO -c "read 2T 4k" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== Negative extent size =="
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+_use_sample_img empty.bochs.bz2
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+poke_file "$TEST_IMG" "$extent_size_offset" "\xff\xff\xff\xff"
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+{ $QEMU_IO -c "read 768k 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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+echo
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+echo "== Zero extent size =="
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+_use_sample_img empty.bochs.bz2
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+poke_file "$TEST_IMG" "$extent_size_offset" "\x00\x00\x00\x00"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+
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 # success, all done
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 echo "*** done"
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 rm -f $seq.full
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diff --git a/tests/qemu-iotests/078.out b/tests/qemu-iotests/078.out
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index 7254693..ea95ffd 100644
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--- a/tests/qemu-iotests/078.out
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+++ b/tests/qemu-iotests/078.out
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@@ -15,4 +15,12 @@ no file open, try 'help open'
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 == Too small catalog bitmap for image size ==
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 qemu-io: can't open device TEST_DIR/empty.bochs: Catalog size is too small for this disk size
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 no file open, try 'help open'
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+
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+== Negative extent size ==
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+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size 4294967295 is too large
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+no file open, try 'help open'
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+
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+== Zero extent size ==
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+qemu-io: can't open device TEST_DIR/empty.bochs: Extent size may not be zero
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+no file open, try 'help open'
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 *** done
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-- 
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1.7.1
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