details: http://hg.nginx.org/nginx/rev/d0b897c0bb5b
branches:
changeset: 7283:d0b897c0bb5b
user: Roman Arutyunyan <arut@nginx.com>
date: Fri Jun 01 16:53:02 2018 +0300
description:
Events: fixed handling zero-length client address.

On Linux recvmsg() syscall may return a zero-length client address when
receiving a datagram from an unbound unix datagram socket. It is usually
assumed that socket address has at least the sa_family member. Zero-length
socket address caused buffer over-read in functions which receive socket
address, for example ngx_sock_ntop(). Typically the over-read resulted in
unexpected socket family followed by session close. Now a fake socket address
is allocated instead of a zero-length client address.

diffstat:

src/event/ngx_event_accept.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)

diffs (22 lines):

diff -r da9941c9b01b -r d0b897c0bb5b src/event/ngx_event_accept.c
--- a/src/event/ngx_event_accept.c Mon Jun 04 18:47:54 2018 +0300
+++ b/src/event/ngx_event_accept.c Fri Jun 01 16:53:02 2018 +0300
@@ -448,6 +448,18 @@ ngx_event_recvmsg(ngx_event_t *ev)
c->socklen = sizeof(ngx_sockaddr_t);
}

+ if (c->socklen == 0) {
+
+ /*
+ * on Linux recvmsg() returns zero msg_namelen
+ * when receiving packets from unbound AF_UNIX sockets
+ */
+
+ c->socklen = sizeof(struct sockaddr);
+ ngx_memzero(&sa, sizeof(struct sockaddr));
+ sa.sockaddr.sa_family = ls->sockaddr->sa_family;
+ }
+
#if (NGX_STAT_STUB)
(void) ngx_atomic_fetch_add(ngx_stat_active, 1);
#endif
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