details: http://hg.nginx.org/nginx/rev/5c25f01bbd52
branches: stable-1.12
changeset: 7146:5c25f01bbd52
user: Maxim Dounin <mdounin@mdounin.ru>
date: Wed Oct 04 21:19:38 2017 +0300
description:
Fixed handling of non-null-terminated unix sockets.

At least FreeBSD, macOS, NetBSD, and OpenBSD can return unix sockets
with non-null-terminated sun_path. Additionally, the address may become
non-null-terminated if it does not fit into the buffer provided and was
truncated (may happen on macOS, NetBSD, and Solaris, which allow unix socket
addresess larger than struct sockaddr_un). As such, ngx_sock_ntop() might
overread the sockaddr provided, as it used "%s" format and thus assumed
null-terminated string.

To fix this, the ngx_strnlen() function was introduced, and it is now used
to calculate correct length of sun_path.

diffstat:

src/core/ngx_inet.c | 4 +++-
src/core/ngx_string.c | 16 ++++++++++++++++
src/core/ngx_string.h | 2 ++
3 files changed, 21 insertions(+), 1 deletions(-)

diffs (52 lines):

diff --git a/src/core/ngx_inet.c b/src/core/ngx_inet.c
--- a/src/core/ngx_inet.c
+++ b/src/core/ngx_inet.c
@@ -241,7 +241,9 @@ ngx_sock_ntop(struct sockaddr *sa, sockl
p = ngx_snprintf(text, len, "unix:%Z");

} else {
- p = ngx_snprintf(text, len, "unix:%s%Z", saun->sun_path);
+ n = ngx_strnlen((u_char *) saun->sun_path,
+ socklen - offsetof(struct sockaddr_un, sun_path));
+ p = ngx_snprintf(text, len, "unix:%*s%Z", n, saun->sun_path);
}

/* we do not include trailing zero in address length */
diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -29,6 +29,22 @@ ngx_strlow(u_char *dst, u_char *src, siz
}


+size_t
+ngx_strnlen(u_char *p, size_t n)
+{
+ size_t i;
+
+ for (i = 0; i < n; i++) {
+
+ if (p[i] == '\0') {
+ return i;
+ }
+ }
+
+ return n;
+}
+
+
u_char *
ngx_cpystrn(u_char *dst, u_char *src, size_t n)
{
diff --git a/src/core/ngx_string.h b/src/core/ngx_string.h
--- a/src/core/ngx_string.h
+++ b/src/core/ngx_string.h
@@ -60,6 +60,8 @@ void ngx_strlow(u_char *dst, u_char *src
#define ngx_strstr(s1, s2) strstr((const char *) s1, (const char *) s2)
#define ngx_strlen(s) strlen((const char *) s)

+size_t ngx_strnlen(u_char *p, size_t n);
+
#define ngx_strchr(s1, c) strchr((const char *) s1, (int) c)

static ngx_inline u_char *
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