提交 2ebafc85 编写于 作者: K Kevin Wolf

qcow2: Fix header extension size check

After reading the extension header, offset is incremented, but not
checked against end_offset any more. This way an integer overflow could
happen when checking whether the extension end is within the allowed
range, effectively disabling the check.

This patch adds the missing check and a test case for it.

Cc: qemu-stable@nongnu.org
Reported-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 1416935562-7760-2-git-send-email-kwolf@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
上级 3dc7ca3c
......@@ -117,7 +117,7 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
#ifdef DEBUG_EXT
printf("ext.magic = 0x%x\n", ext.magic);
#endif
if (ext.len > end_offset - offset) {
if (offset > end_offset || ext.len > end_offset - offset) {
error_setg(errp, "Header extension too large");
return -EINVAL;
}
......
......@@ -78,6 +78,8 @@ poke_file "$TEST_IMG" "$offset_backing_file_offset" "\xff\xff\xff\xff\xff\xff\xf
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" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x00\x$(printf %x $offset_ext_size)"
{ $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
......
......@@ -13,6 +13,8 @@ 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'
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
......
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