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| author | Kevin Wolf <kwolf@redhat.com> | 2014-03-26 13:05:42 +0100 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-04-01 14:19:09 +0200 |
| commit | a1b3955c9415b1e767c130a2f59fee6aa28e575b (patch) | |
| tree | c4560b854410ca2629eb5f6c2512664fa180d206 | |
| parent | 24342f2cae47d03911e346fe1e520b00dc2818e0 (diff) | |
| download | qemu-a1b3955c9415b1e767c130a2f59fee6aa28e575b.tar.gz | |
qcow2: Check backing_file_offset (CVE-2014-0144)
Header, header extension and the backing file name must all be stored in
the first cluster. Setting the backing file to a much higher value
allowed header extensions to become much bigger than we want them to be
(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>
| -rw-r--r-- | block/qcow2.c | 6 | ||||
| -rwxr-xr-x | tests/qemu-iotests/080 | 12 | ||||
| -rw-r--r-- | tests/qemu-iotests/080.out | 7 |
3 files changed, 25 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 7809f5cab4..f0411a9217 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -511,6 +511,12 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags, } } + if (header.backing_file_offset > s->cluster_size) { + error_setg(errp, "Invalid backing file offset"); + ret = -EINVAL; + goto fail; + } + if (header.backing_file_offset) { ext_end = header.backing_file_offset; } else { diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080 index 6512701e1e..6d588ddd12 100755 --- a/tests/qemu-iotests/080 +++ b/tests/qemu-iotests/080 @@ -43,6 +43,8 @@ _supported_proto generic _supported_os Linux header_size=104 + +offset_backing_file_offset=8 offset_header_size=100 offset_ext_magic=$header_size offset_ext_size=$((header_size + 4)) @@ -55,6 +57,16 @@ poke_file "$TEST_IMG" "$offset_header_size" "\xff\xff\xff\xff" poke_file "$TEST_IMG" "$offset_header_size" "\x7f\xff\xff\xff" { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir +echo +echo "== Huge unknown header extension ==" +_make_test_img 64M +poke_file "$TEST_IMG" "$offset_backing_file_offset" "\xff\xff\xff\xff\xff\xff\xff\xff" +poke_file "$TEST_IMG" "$offset_ext_magic" "\x12\x34\x56\x78" +poke_file "$TEST_IMG" "$offset_ext_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_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 + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out index 41a166a27f..48c40aa3e2 100644 --- a/tests/qemu-iotests/080.out +++ b/tests/qemu-iotests/080.out @@ -6,4 +6,11 @@ qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size no file open, try 'help open' qemu-io: can't open device TEST_DIR/t.qcow2: qcow2 header exceeds cluster size no file open, try 'help open' + +== Huge unknown header extension == +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 +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' *** done |