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Changed strlen to lua_strlen for producers key and value #22

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Merged
merged 2 commits into from
Jan 22, 2021
Merged

Changed strlen to lua_strlen for producers key and value #22

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919a7ad
Changed strlen to lua_strlen for producers key and value
Jun 12, 2020
66a4192
Replace function lua_tostring with lua_tolstring.
Jun 16, 2020
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12 changes: 6 additions & 6 deletions kafka/producer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -332,19 +332,19 @@ lua_producer_produce(struct lua_State *L) {

lua_pushstring(L, "key");
lua_gettable(L, -2 );
size_t key_len;
// rd_kafka will copy key so no need to worry about this cast
char *key = (char *)lua_tostring(L, -1);
lua_pop(L, 1);
char *key = (char *)lua_tolstring(L, -1, &key_len);

size_t key_len = key != NULL ? strlen(key) : 0;
lua_pop(L, 1);
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Well, as we discussed in Tarantool-ru telegram chat, this approach could lead to use-after-free (https://pgl.yoyo.org/luai/i/lua_tolstring)

Maybe we should use luaL_ref/luaL_unref here.

Also it would be great to add a test for such case.

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The problem of use after free was present before (and I suppose this is another issue), this PR just replace strlen to lua_tolstring

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Well, you are right. I don't have objections.

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this approach could lead to use-after-free

@filonenko-mikhail @olegrok please confirm or deny that this issue has been fixed till the current day's release.

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I think to problem still exists


lua_pushstring(L, "value");
lua_gettable(L, -2 );
size_t value_len;
// rd_kafka will copy value so no need to worry about this cast
char *value = (char *)lua_tostring(L, -1);
lua_pop(L, 1);
char *value = (char *)lua_tolstring(L, -1, &value_len);

size_t value_len = value != NULL ? strlen(value) : 0;
lua_pop(L, 1);

if (key == NULL && value == NULL) {
int fail = safe_pushstring(L, "producer message must contains non nil key or value");
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