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qcow2: Validate refcount table offset

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The end of the refcount table must not exceed INT64_MAX so that integer
overflows are avoided.

Also check for misaligned refcount table. Such images are invalid and
probably the result of data corruption. Error out to avoid further
corruption.

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 13:05:44 +01:00 • committed by Stefan Hajnoczi
parent 5dab2faddc
commit 8c7de28305
3 changed files with 56 additions and 0 deletions
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13
tests/qemu-iotests/080
View file

@ -45,6 +45,7 @@ _supported_os Linux
header_size=104
offset_backing_file_offset=8
offset_refcount_table_offset=48
offset_refcount_table_clusters=56
offset_header_size=100
offset_ext_magic=$header_size
@ -76,6 +77,18 @@ poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\xff\xff\xff\xff"
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x02\x00\x01"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Misaligned refcount table =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Huge refcount offset =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\x00\x00\x00\x7f"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
# success, all done
echo "*** done"

10
tests/qemu-iotests/080.out
View file

@ -20,4 +20,14 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Reference count table too large
no file open, try 'help open'
== Misaligned refcount table ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
qemu-io: can't open device TEST_DIR/t.qcow2: Invalid reference count table offset
no file open, try 'help open'
== Huge refcount offset ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
qemu-io: can't open device TEST_DIR/t.qcow2: Invalid reference count table offset
no file open, try 'help open'
*** done