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Guard JSON container size with compile-time bound #11

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Merged
jserv merged 1 commit into from
May 13, 2026
+10 −0
Merged

Guard JSON container size with compile-time bound #11

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10 changes: 10 additions & 0 deletions lib/json.c
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Original file line number Diff line number Diff line change
Expand Up @@ -229,6 +229,16 @@ static bool jp_match(struct json_parser *p, const char *s, sz len)

#define JSON_CONTAINER_MAX 64

/* Bound the per-container element count so that 'count * sizeof(element)'
* is provably representable in 'sz' and cannot wrap. Callers further down
* pass 'count' to arena_alloc_array() and memcpy(); without this compile
* time bound the multiplication would need a runtime overflow guard.
*/
static_assert(JSON_CONTAINER_MAX <= SZ_MAX / sizeof(struct json_value),
"JSON_CONTAINER_MAX too large for json_value allocation");
static_assert(JSON_CONTAINER_MAX <= SZ_MAX / sizeof(struct json_kv),
"JSON_CONTAINER_MAX too large for json_kv allocation");

static struct json_result jp_parse_array(struct json_parser *p)
{
if (p->depth >= JSON_MAX_DEPTH)
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