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Fixed bug #80761

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When row data split across multiple packets, allocate a temporary
buffer that can be reallocated, and only copy into the row buffer
pool arena once we know the final size. This avoids quadratic
memory usage for very large results.
This commit is contained in:
Nikita Popov 2021-02-23 11:14:51 +01:00
parent 8be711be47
commit 1fc4c89214
2 changed files with 30 additions and 35 deletions
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62
ext/mysqlnd/mysqlnd_wireprotocol.c
View file

@ -1381,47 +1381,39 @@ php_mysqlnd_read_row_ex(MYSQLND_PFC * pfc,
SET_CONNECTION_STATE(connection_state, CONN_QUIT_SENT);
set_packet_error(error_info, CR_SERVER_GONE_ERROR, UNKNOWN_SQLSTATE, mysqlnd_server_gone);
} else {
/* If the packet is split in multiple chunks, allocate a temporary buffer that we can
* reallocate, and only afterwards copy it to the pool when we know the final size. */
zend_uchar *buf = NULL;
while (header.size >= MYSQLND_MAX_PACKET_SIZE) {
buf = erealloc(buf, *data_size + header.size);
p = buf + *data_size;
*data_size += header.size;
if (UNEXPECTED(PASS != (ret = pfc->data->m.receive(pfc, vio, p, header.size, stats, error_info)))) {
DBG_ERR("Empty row packet body");
SET_CONNECTION_STATE(connection_state, CONN_QUIT_SENT);
set_packet_error(error_info, CR_SERVER_GONE_ERROR, UNKNOWN_SQLSTATE, mysqlnd_server_gone);
efree(buf);
DBG_RETURN(FAIL);
}
if (FAIL == mysqlnd_read_header(pfc, vio, &header, stats, error_info)) {
efree(buf);
DBG_RETURN(FAIL);
}
}
buffer->ptr = pool->get_chunk(pool, *data_size + header.size + prealloc_more_bytes);
if (buf) {
memcpy(buffer->ptr, buf, *data_size);
efree(buf);
}
p = buffer->ptr + *data_size;
*data_size += header.size;
buffer->ptr = pool->get_chunk(pool, *data_size + prealloc_more_bytes);
p = buffer->ptr;
if (UNEXPECTED(PASS != (ret = pfc->data->m.receive(pfc, vio, p, header.size, stats, error_info)))) {
DBG_ERR("Empty row packet body");
SET_CONNECTION_STATE(connection_state, CONN_QUIT_SENT);
set_packet_error(error_info, CR_SERVER_GONE_ERROR, UNKNOWN_SQLSTATE, mysqlnd_server_gone);
} else {
while (header.size >= MYSQLND_MAX_PACKET_SIZE) {
if (FAIL == mysqlnd_read_header(pfc, vio, &header, stats, error_info)) {
ret = FAIL;
break;
}
*data_size += header.size;
/* Empty packet after MYSQLND_MAX_PACKET_SIZE packet. That's ok, break */
if (!header.size) {
break;
}
/*
We have to realloc the buffer.
*/
buffer->ptr = pool->resize_chunk(pool, buffer->ptr, *data_size - header.size, *data_size + prealloc_more_bytes);
if (!buffer->ptr) {
SET_OOM_ERROR(error_info);
ret = FAIL;
break;
}
/* The position could have changed, recalculate */
p = (zend_uchar *) buffer->ptr + (*data_size - header.size);
if (PASS != (ret = pfc->data->m.receive(pfc, vio, p, header.size, stats, error_info))) {
DBG_ERR("Empty row packet body");
SET_CONNECTION_STATE(connection_state, CONN_QUIT_SENT);
set_packet_error(error_info, CR_SERVER_GONE_ERROR, UNKNOWN_SQLSTATE, mysqlnd_server_gone);
break;
}
}
}
}
if (ret == FAIL && buffer->ptr) {