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From ffbffdc438191db5bfa6ae6da52f0578db0fe7ac 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 14:23:28 +0100
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Subject: [PATCH 21/49] qcow2: Check backing_file_offset (CVE-2014-0144)
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-22-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 21/48] qcow2: Check backing_file_offset (CVE-2014-0144)
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Bugzilla: 1079455
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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=1079455
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Upstream status: Embargoed
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Header, header extension and the backing file name must all be stored in
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the first cluster. Setting the backing file to a much higher value
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allowed header extensions to become much bigger than we want them to be
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(unbounded allocation).
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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block/qcow2.c | 6 ++++++
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tests/qemu-iotests/080 | 12 ++++++++++++
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tests/qemu-iotests/080.out | 7 +++++++
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3 files changed, 25 insertions(+), 0 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index ea51f8e..5568cf9 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -511,6 +511,12 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
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}
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}
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+ if (header.backing_file_offset > s->cluster_size) {
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+ error_setg(errp, "Invalid backing file offset");
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+ ret = -EINVAL;
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+ goto fail;
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+ }
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+
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if (header.backing_file_offset) {
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ext_end = header.backing_file_offset;
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} else {
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diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
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index 6512701..6d588dd 100755
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--- a/tests/qemu-iotests/080
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+++ b/tests/qemu-iotests/080
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@@ -43,6 +43,8 @@ _supported_proto generic
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_supported_os Linux
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header_size=104
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+
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+offset_backing_file_offset=8
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offset_header_size=100
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offset_ext_magic=$header_size
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offset_ext_size=$((header_size + 4))
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@@ -55,6 +57,16 @@ poke_file "$TEST_IMG" "$offset_header_size" "\xff\xff\xff\xff"
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poke_file "$TEST_IMG" "$offset_header_size" "\x7f\xff\xff\xff"
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{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+echo
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+echo "== Huge unknown header extension =="
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+_make_test_img 64M
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+poke_file "$TEST_IMG" "$offset_backing_file_offset" "\xff\xff\xff\xff\xff\xff\xff\xff"
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+poke_file "$TEST_IMG" "$offset_ext_magic" "\x12\x34\x56\x78"
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+poke_file "$TEST_IMG" "$offset_ext_size" "\x7f\xff\xff\xff"
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+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
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+poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\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/080.out b/tests/qemu-iotests/080.out
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index 41a166a..48c40aa 100644
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--- a/tests/qemu-iotests/080.out
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+++ b/tests/qemu-iotests/080.out
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@@ -6,4 +6,11 @@ qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
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no file open, try 'help open'
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qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size
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no file open, try 'help open'
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+
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+== Huge unknown header extension ==
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+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
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+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid backing file offset
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+no file open, try 'help open'
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+qemu-io: can't open device TEST_DIR/t.qcow2: Header extension too large
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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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