qcow2: Check refcount table size (CVE-2014-0144)

Limit the in-memory reference count table size to 8 MB, it's enough in
practice. This fixes an unbounded allocation as well as a buffer
overflow in qcow2_refcount_init().

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 13:05:43 +01:00 committed by Stefan Hajnoczi
parent a1b3955c94
commit 5dab2faddc
4 changed files with 29 additions and 1 deletions

View file

@ -45,6 +45,7 @@ _supported_os Linux
header_size=104
offset_backing_file_offset=8
offset_refcount_table_clusters=56
offset_header_size=100
offset_ext_magic=$header_size
offset_ext_size=$((header_size + 4))
@ -67,6 +68,15 @@ poke_file "$TEST_IMG" "$offset_ext_size" "\x7f\xff\xff\xff"
poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
echo
echo "== Huge refcount table size =="
_make_test_img 64M
poke_file "$TEST_IMG" "$offset_refcount_table_clusters" "\xff\xff\xff\xff"
{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
poke_file "$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
# success, all done
echo "*** done"
rm -f $seq.full

View file

@ -13,4 +13,11 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Invalid backing file offset
no file open, try 'help open'
qemu-io: can't open device TEST_DIR/t.qcow2: Header extension too large
no file open, try 'help open'
== Huge refcount table size ==
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
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'
*** done