segfault in `lyd_parse_data`

[jktjkt]

With the most recent devel of libyang, the libyang-cpp's test suite started failing when parsing this malformed JSON data:

{"example-schema5:x_b":{"x_b_leaf":"wtf"}}

Apparently, the C library dereferences a null pointer in https://github.com/CESNET/libyang/blob/devel/src/parser_common.c#L484 , the first_p is NULL during this test.

libyang[0]: Invalid non-number-encoded int32 value "wtf". (data path: /example-schema5:x/x_b/x_b_leaf, line: 1)
github/CESNET/libyang/src/parser_common.c:484:9: runtime error: load of null pointer of type 'struct lyd_node *'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior github/CESNET/libyang/src/parser_common.c:484:9 

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff75e06d9 in lyd_parser_node_free (first_p=first_p@entry=0x0, node=0x7bfff475b230) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_common.c:484
484         if (*first_p && !(*first_p)->parent && (*first_p == *node)) {
(gdb) bt
#0  0x00007ffff75e06d9 in lyd_parser_node_free (first_p=first_p@entry=0x0, node=0x7bfff475b230) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_common.c:484
#1  0x00007ffff73f9065 in lydjson_parse_instance_inner (lydctx=0x7e0ff58b2100, snode=0x7cbff5e3b000, ext=0x0, parent=0x7c6ff5acf4e0, first_p=0x0, status=<optimized out>, node=<optimized out>) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_json.c:1453
#2  lydjson_parse_instance (lydctx=0x7e0ff58b2100, parent=<optimized out>, first_p=<optimized out>, snode=0x7cbff5e3b000, ext=<optimized out>, name=<optimized out>, name_len=<optimized out>, prefix=<optimized out>, prefix_len=<optimized out>, status=<optimized out>, node=<optimized out>) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_json.c:1522
#3  0x00007ffff73ee6ca in lydjson_subtree_r (lydctx=0x7e0ff58b2100, parent=<optimized out>, first_p=<optimized out>, parsed=<optimized out>) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_json.c:1762
#4  0x00007ffff73e9cef in lyd_parse_json (ctx=0x7d1ff622be40, ext=<optimized out>, parent=<optimized out>, schema=0x0, first_p=<optimized out>, in=0x7c6ff5acf5c0, parse_opts=<optimized out>, val_opts=<optimized out>, int_opts=<optimized out>, parsed=<optimized out>, subtree_sibling=<optimized out>, lydctx_p=<optimized out>)
    at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/parser_json.c:1990
#5  0x00007ffff73402cd in lyd_parse (ctx=0x7d1ff622be40, ext=<optimized out>, parent=<optimized out>, first_p=<optimized out>, in=<optimized out>, format=<optimized out>, parse_opts=<optimized out>, val_opts=<optimized out>, op=0x0) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/tree_data.c:135
#6  0x00007ffff7340fa1 in lyd_parse_data (ctx=0x0, parent=<optimized out>, in=0x7c6ff5acf5c0, format=LYD_JSON, parse_options=720896, validate_options=0, tree=0x0) at /home/jkt/work/cesnet/gerrit/github/CESNET/libyang/src/tree_data.c:239
#7  0x00007ffff7f01018 in libyang::DataNode::parseSubtree (this=<optimized out>, data=..., format=<optimized out>, parseOpts=Python Exception <class 'gdb.error'>: value has been optimized out
..., validationOpts=std::optional [no contained value]) at /home/jkt/work/cesnet/gerrit/CzechLight/libyang-cpp/src/DataNode.cpp:1307
#8  0x0000555555767f8d in DOCTEST_ANON_FUNC_2 () at /home/jkt/work/cesnet/gerrit/CzechLight/libyang-cpp/tests/data_node.cpp:1858
#9  0x000055555581603c in doctest::Context::run (this=0x7bfff4300020) at /home/jkt/work/prog/_build/czechlight-clang20-asan-ubsan/target/include/doctest/doctest.h:7007
#10 0x000055555581be4d in main (argc=1, argv=<optimized out>) at /home/jkt/work/prog/_build/czechlight-clang20-asan-ubsan/target/include/doctest/doctest.h:7085

[michalvasko]

Thanks, should be fixed.