From c375a7efa3a42afc51385659437f04027ed106b1 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 23 Sep 2016 00:37:53 -0400 Subject: ident: handle NULL ai_canonname We call getaddrinfo() to try to convert a short hostname into a fully-qualified one (to use it as an email domain). If there isn't a canonical name, getaddrinfo() will generally return either a NULL addrinfo list, or one in which ai->ai_canonname is a copy of the original name. However, if the result of gethostname() looks like an IP address, then getaddrinfo() behaves differently on some systems. On OS X, it will return a "struct addrinfo" with a NULL ai_canonname, and we segfault feeding it to strchr(). This is hard to test reliably because it involves not only a system where we we have to fallback to gethostname() to come up with an ident, but also where the hostname is a number with no dots. But I was able to replicate the bug by faking a hostname, like: diff --git a/ident.c b/ident.c index e20a772..b790d28 100644 --- a/ident.c +++ b/ident.c @@ -128,6 +128,7 @@ static void add_domainname(struct strbuf *out, int *is_bogus) *is_bogus = 1; return; } + xsnprintf(buf, sizeof(buf), "1"); if (strchr(buf, '.')) strbuf_addstr(out, buf); else if (canonical_name(buf, out) < 0) { and running "git var GIT_AUTHOR_IDENT" on an OS X system. Before this patch it segfaults, and after we correctly complain of the bogus "user@1.(none)" address (though this bogus address would be suitable for non-object uses like writing reflogs). Reported-by: Jonas Thiel Diagnosed-by: John Keeping Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- ident.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'ident.c') diff --git a/ident.c b/ident.c index 4fd82d1043..28bc854918 100644 --- a/ident.c +++ b/ident.c @@ -103,7 +103,7 @@ static int canonical_name(const char *host, struct strbuf *out) memset (&hints, '\0', sizeof (hints)); hints.ai_flags = AI_CANONNAME; if (!getaddrinfo(host, NULL, &hints, &ai)) { - if (ai && strchr(ai->ai_canonname, '.')) { + if (ai && ai->ai_canonname && strchr(ai->ai_canonname, '.')) { strbuf_addstr(out, ai->ai_canonname); status = 0; } -- cgit v1.2.3