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[Net] Fix Marshalls infinite recursion crash.

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Variants like dictionaries and arrays can have cyclic references, which
caused `encode_variant` to run an infinite recursion.
Instead of keeping a stack and looking for cyclic references which would
make serialization slower, this commit adds a `MAX_RECURSION_DEPTH`
constant to Variant, and have `encode_variant` keep track of the current
recursion depth, bailing when it's too high since this likely means a
cyclic reference has been encountered.

(cherry picked from commit 324636473a)
This commit is contained in:
Fabio Alessandrelli 2021-07-30 15:43:01 +02:00 committed by Rémi Verschelde
parent 8f592d50c3
commit ccbd810934
No known key found for this signature in database
GPG key ID: C3336907360768E1
3 changed files with 16 additions and 9 deletions
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18
core/io/marshalls.cpp
View file

@ -763,7 +763,8 @@ static void _encode_string(const String &p_string, uint8_t *&buf, int &r_len) {
} }
} }
Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bool p_full_objects) { Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bool p_full_objects, int p_depth) {
ERR_FAIL_COND_V_MSG(p_depth > Variant::MAX_RECURSION_DEPTH, ERR_OUT_OF_MEMORY, "Potential inifite recursion detected. Bailing.");
uint8_t *buf = r_buffer; uint8_t *buf = r_buffer;
r_len = 0; r_len = 0;
@ -1076,10 +1077,8 @@ Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bo
_encode_string(E->get().name, buf, r_len); _encode_string(E->get().name, buf, r_len);
int len; int len;
Error err = encode_variant(obj->get(E->get().name), buf, len, p_full_objects); Error err = encode_variant(obj->get(E->get().name), buf, len, p_full_objects, p_depth + 1);
if (err) { ERR_FAIL_COND_V(err, err);
return err;
}
ERR_FAIL_COND_V(len % 4, ERR_BUG); ERR_FAIL_COND_V(len % 4, ERR_BUG);
r_len += len; r_len += len;
if (buf) { if (buf) {
@ -1130,13 +1129,15 @@ Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bo
*/ */
Variant *v = d.getptr(E->get()); Variant *v = d.getptr(E->get());
int len; int len;
encode_variant(v ? E->get() : Variant("[Deleted Object]"), buf, len, p_full_objects); Error err = encode_variant(v ? E->get() : Variant("[Deleted Object]"), buf, len, p_full_objects, p_depth + 1);
ERR_FAIL_COND_V(err, err);
ERR_FAIL_COND_V(len % 4, ERR_BUG); ERR_FAIL_COND_V(len % 4, ERR_BUG);
r_len += len; r_len += len;
if (buf) { if (buf) {
buf += len; buf += len;
} }
encode_variant(v ? *v : Variant(), buf, len, p_full_objects); err = encode_variant(v ? *v : Variant(), buf, len, p_full_objects, p_depth + 1);
ERR_FAIL_COND_V(err, err);
ERR_FAIL_COND_V(len % 4, ERR_BUG); ERR_FAIL_COND_V(len % 4, ERR_BUG);
r_len += len; r_len += len;
if (buf) { if (buf) {
@ -1157,7 +1158,8 @@ Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bo
for (int i = 0; i < v.size(); i++) { for (int i = 0; i < v.size(); i++) {
int len; int len;
encode_variant(v.get(i), buf, len, p_full_objects); Error err = encode_variant(v.get(i), buf, len, p_full_objects, p_depth + 1);
ERR_FAIL_COND_V(err, err);
ERR_FAIL_COND_V(len % 4, ERR_BUG); ERR_FAIL_COND_V(len % 4, ERR_BUG);
r_len += len; r_len += len;
if (buf) { if (buf) {

2
core/io/marshalls.h
View file

@ -181,6 +181,6 @@ public:
}; };
Error decode_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len = nullptr, bool p_allow_objects = false); Error decode_variant(Variant &r_variant, const uint8_t *p_buffer, int p_len, int *r_len = nullptr, bool p_allow_objects = false);
Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bool p_full_objects = false); Error encode_variant(const Variant &p_variant, uint8_t *r_buffer, int &r_len, bool p_full_objects = false, int p_depth = 0);
#endif #endif

5
core/variant.h
View file

@ -136,6 +136,11 @@ public:
}; };
enum {
// Maximum recursion depth allowed when serializing variants.
MAX_RECURSION_DEPTH = 1024,
};
private: private:
friend struct _VariantCall; friend struct _VariantCall;
// Variant takes 20 bytes when real_t is float, and 36 if double // Variant takes 20 bytes when real_t is float, and 36 if double