Fixed segfault when switching off master process during upgrade. Binary upgrades are not supported without master process, but it is, however, possible, that nginx running with master process is asked to upgrade binary, and the configuration file as available on disk at this time includes "master_process off;". If this happens, listening sockets inherited from the previous binary will have ls[i].previous set. But the old cycle on initial process startup, including startup after binary upgrade, is destroyed by ngx_init_cycle() once configuration parsing is complete. As a result, an attempt to dereference ls[i].previous in ngx_event_process_init() accesses already freed memory. Fix is to avoid looking into ls[i].previous if the old cycle is already freed. With this change it is also no longer needed to clear ls[i].previous in worker processes, so the relevant code was removed.

/*
 * Copyright (C) Roman Arutyunyan
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_PROXY_PROTOCOL_H_INCLUDED_
#define _NGX_PROXY_PROTOCOL_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


#define NGX_PROXY_PROTOCOL_V1_MAX_HEADER  107
#define NGX_PROXY_PROTOCOL_MAX_HEADER     4096


struct ngx_proxy_protocol_s {
    ngx_str_t           src_addr;
    ngx_str_t           dst_addr;
    in_port_t           src_port;
    in_port_t           dst_port;
    ngx_str_t           tlvs;
};


u_char *ngx_proxy_protocol_read(ngx_connection_t *c, u_char *buf,
    u_char *last);
u_char *ngx_proxy_protocol_write(ngx_connection_t *c, u_char *buf,
    u_char *last);
ngx_int_t ngx_proxy_protocol_get_tlv(ngx_connection_t *c, ngx_str_t *name,
    ngx_str_t *value);


#endif /* _NGX_PROXY_PROTOCOL_H_INCLUDED_ */