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qcow2: Validate active L1 table offset and size (CVE-2014-0144)

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This avoids an unbounded allocation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2014-03-26 13:05:46 +01:00 committed by Stefan Hajnoczi
parent ce48f2f441
commit 2d51c32c4b
3 changed files with 45 additions and 0 deletions
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16
block/qcow2.c
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@ -642,6 +642,13 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
s->nb_snapshots = header.nb_snapshots;
/* read the level 1 table */
if (header.l1_size > 0x2000000) {
/* 32 MB L1 table is enough for 2 PB images at 64k cluster size
* (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
error_setg(errp, "Active L1 table too large");
ret = -EFBIG;
goto fail;
}
s->l1_size = header.l1_size;
l1_vm_state_index = size_to_l1(s, header.size);
@ -659,7 +666,16 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
ret = -EINVAL;
goto fail;
}
ret = validate_table_offset(bs, header.l1_table_offset,
header.l1_size, sizeof(uint64_t));
if (ret < 0) {
error_setg(errp, "Invalid L1 table offset");
goto fail;
}
s->l1_table_offset = header.l1_table_offset;
if (s->l1_size > 0) {
s->l1_table = g_malloc0(
align_offset(s->l1_size * sizeof(uint64_t), 512));

18
tests/qemu-iotests/080
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@ -45,6 +45,8 @@ _supported_os Linux
header_size=104
offset_backing_file_offset=8
offset_l1_size=36
offset_l1_table_offset=40
offset_refcount_table_offset=48
offset_refcount_table_clusters=56
offset_nb_snapshots=60
@ -117,6 +119,22 @@ poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x01\x00\x00"
{ $QEMU_IMG snapshot -c test $TEST_IMG; } 2>&1 | _filter_testdir
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Invalid L1 table =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_l1_size" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_size" "\x7f\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x7f\xff\xff\xff\xff\xff\x00\x00"
poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
# success, all done
echo "*** done"
rm -f $seq.full

11
tests/qemu-iotests/080.out
View File

@ -47,4 +47,15 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
qemu-img: Could not create snapshot 'test': -27 (File too large)
read 512/512 bytes at offset 0
512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
== Invalid L1 table ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Active L1 table too large
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset
no file open, try 'help open'
*** done