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qobject_from_json() & friends use the consume_json() callback to receive either a value or an error from the parser. When they are fed a string that contains more than either one JSON value or one JSON syntax error, consume_json() gets called multiple times. When the last call receives a value, qobject_from_json() returns that value. Any other values are leaked. When any call receives an error, qobject_from_json() sets the first error received. Any other errors are thrown away. When values follow errors, qobject_from_json() returns both a value and sets an error. That's bad. Impact: * block.c's parse_json_protocol() ignores and leaks the value. It's used to to parse pseudo-filenames starting with "json:". The pseudo-filenames can come from the user or from image meta-data such as a QCOW2 image's backing file name. * vl.c's parse_display_qapi() ignores and leaks the error. It's used to parse the argument of command line option -display. * vl.c's main() case QEMU_OPTION_blockdev ignores the error and leaves it in @err. main() will then pass a pointer to a non-null Error * to net_init_clients(), which is forbidden. It can lead to assertion failure or other misbehavior. * check-qjson.c's multiple_values() demonstrates the badness. * The other callers are not affected since they only pass strings with exactly one JSON value or, in the case of negative tests, one error. The impact on the _nofail() functions is relatively harmless. They abort when any call receives an error. Else they return the last value, and leak the others, if any. Fix consume_json() as follows. On the first call, save value and error as before. On subsequent calls, if any, don't save them. If the first call saved a value, the next call, if any, replaces the value by an "Expecting at most one JSON value" error. Take care not to leak values or errors that aren't saved. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20180823164025.12553-44-armbru@redhat.com> |
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| .. | ||
| block-qdict.c | ||
| json-lexer.c | ||
| json-parser.c | ||
| json-streamer.c | ||
| Makefile.objs | ||
| qbool.c | ||
| qdict.c | ||
| qjson.c | ||
| qlist.c | ||
| qlit.c | ||
| qnull.c | ||
| qnum.c | ||
| qobject.c | ||
| qstring.c | ||