commit 2e88368b94ea5614d8854ab94f7516b95e1ac4a6
author Juraj Vijtiuk <juraj.vijtiuk@sartura.hr> Mon Sep 20 17:00:56 2021 +0200
committer Michal Vasko <mvasko@cesnet.cz> Thu Sep 23 13:41:39 2021 +0200
tree b69e325002dcdd915347728d60a971df3336baa0
parent 107c816d8caa207133b3a852d3bc6dc672330e4f

parser json BUGFIX parsing object key-value pair in lydjson_data_skip()

After a key-value pair was successfully parsed in lydjson_data_skip()
lyjson_ctx_next() parses the next key and returns LYJSON_OBJECT.
Add a missing check to see whether a nested object was actually parsed
or whether it was the next key.

Remove sublevel checks for LYJSON_OBJECT_EMPTY and LYJSON_ARRAY_EMPTY.
In the case of empty objects, jsonctx->depth doesn't change after calling
lyjson_ctx_next(), so sublevel is never increased.

This issue was found by OSS-Fuzz in lyd_parse_mem_json.

Signed-off-by: Juraj Vijtiuk <juraj.vijtiuk@sartura.hr>

src/parser_json.c

diff --git a/src/parser_json.c b/src/parser_json.c
index 095705b..e2ed9ae 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -287,12 +287,23 @@
 
     /* skip after the content */
     do {
+        uint32_t prev_depth = jsonctx->depth;
+
         LY_CHECK_RET(lyjson_ctx_next(jsonctx, &current));
+
         if (current == status) {
+            /* lyjson_ctx_next() can return LYSJON_OBJECT in two cases, either when
+             * a new object is encountered, or when it finishes parsing a value from a
+             * previous key-value pair. In the latter case the sublevel shouldn't increase.
+            */
+            if ((status == LYJSON_OBJECT) && (prev_depth == jsonctx->depth)) {
+                continue;
+            }
+
             sublevels++;
-        } else if ((status == LYJSON_OBJECT) && ((current == LYJSON_OBJECT_CLOSED) || (current == LYJSON_OBJECT_EMPTY))) {
+        } else if ((status == LYJSON_OBJECT) && (current == LYJSON_OBJECT_CLOSED)) {
             sublevels--;
-        } else if ((status == LYJSON_ARRAY) && ((current == LYJSON_ARRAY_CLOSED) || (current == LYJSON_ARRAY_EMPTY))) {
+        } else if ((status == LYJSON_ARRAY) && (current == LYJSON_ARRAY_CLOSED)) {
             sublevels--;
         }
     } while (current != status + 1 || sublevels);