qcow2: Validate snapshot table offset/size (CVE-2014-0144)

This avoid unbounded memory allocation and fixes a potential buffer
overflow on 32 bit hosts.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

2 files changed, 44 insertions, 0 deletions

diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
index f58ac73..8a8b460 100755
--- a/tests/qemu-iotests/080
+++ b/tests/qemu-iotests/080
@@ -47,6 +47,8 @@ header_size=104
 offset_backing_file_offset=8
 offset_refcount_table_offset=48
 offset_refcount_table_clusters=56
+offset_nb_snapshots=60
+offset_snapshots_offset=64
 offset_header_size=100
 offset_ext_magic=$header_size
 offset_ext_size=$((header_size + 4))
@@ -90,6 +92,31 @@ poke_file "$TEST_IMG" "$offset_refcount_table_offset" "\xff\xff\xff\xff\xff\xff\
 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
 
+echo
+echo "== Invalid snapshot table =="
+_make_test_img 64M
+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\xff\xff\xff\xff"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x7f\xff\xff\xff"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\xff\xff\xff\xff\xff\xff\x00\x00"
+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\xff\xff"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x12\x34\x56\x78\x90\xab\xcd\xef"
+poke_file "$TEST_IMG" "$offset_nb_snapshots" "\x00\x00\x00\x00"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
+echo
+echo "== Hitting snapshot table size limit =="
+_make_test_img 64M
+# Put the refcount table in a more or less safe place (16 MB)
+poke_file "$TEST_IMG" "$offset_snapshots_offset" "\x00\x00\x00\x00\x01\x00\x00\x00"
+poke_file "$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
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
index f919b58..b06f47f 100644
--- a/tests/qemu-iotests/080.out
+++ b/tests/qemu-iotests/080.out
@@ -30,4 +30,21 @@ no file open, try 'help open'
 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'
+
+== Invalid snapshot table ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
+qemu-io: can't open device TEST_DIR/t.qcow2: Too many snapshots
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.qcow2: Too many snapshots
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid snapshot table offset
+no file open, try 'help open'
+qemu-io: can't open device TEST_DIR/t.qcow2: Invalid snapshot table offset
+no file open, try 'help open'
+
+== Hitting snapshot table size limit ==
+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)
 *** done