Mercurial > hg > nginx
view src/os/unix/ngx_udp_recv.c @ 7048:80224192163c
Resolver: fixed possible use-after-free while resolving SRV.
Resolving an SRV record includes resolving its host names in subrequests.
Previously, if memory allocation failed while reporting a subrequest result
after receiving a response from a DNS server, the SRV resolve handler was
called immediately with the NGX_ERROR state. However, if the SRV record
included another copy of the resolved name, it was reported once again.
This could trigger the use-after-free memory access after SRV resolve
handler freed the resolve context by calling ngx_resolve_name_done().
Now the SRV resolve handler is called only when all its subrequests are
completed.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Tue, 04 Jul 2017 18:07:29 +0300 |
parents | 5ad379eab6fa |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> ssize_t ngx_udp_unix_recv(ngx_connection_t *c, u_char *buf, size_t size) { ssize_t n; ngx_err_t err; ngx_event_t *rev; rev = c->read; do { n = recv(c->fd, buf, size, 0); ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0, "recv: fd:%d %z of %uz", c->fd, n, size); if (n >= 0) { #if (NGX_HAVE_KQUEUE) if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) { rev->available -= n; /* * rev->available may be negative here because some additional * bytes may be received between kevent() and recv() */ if (rev->available <= 0) { rev->ready = 0; rev->available = 0; } } #endif return n; } err = ngx_socket_errno; if (err == NGX_EAGAIN || err == NGX_EINTR) { ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err, "recv() not ready"); n = NGX_AGAIN; } else { n = ngx_connection_error(c, err, "recv() failed"); break; } } while (err == NGX_EINTR); rev->ready = 0; if (n == NGX_ERROR) { rev->error = 1; } return n; }