From 848a95329c867aae726ae990051700c9ef6541fa Mon Sep 17 00:00:00 2001
From: Alejandro Colomar <alx@kernel.org>
Date: Wed, 31 May 2023 12:19:33 +0200
Subject: [PATCH] lib/nss.c: Fix use of uninitialized p

getline(3) might have never succeeded, in which case p is uninitialized
when used in strtok_r(3).

Link: <https://github.com/shadow-maint/shadow/pull/737#discussion_r1206007358>
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---
 lib/nss.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/nss.c b/lib/nss.c
index 1aa27f3e5..e6776fb1a 100644
--- a/lib/nss.c
+++ b/lib/nss.c
@@ -69,7 +69,8 @@ void nss_init(const char *nsswitch_path) {
 		atomic_store(&nss_init_completed, true);
 		return;
 	}
-	while ((getline(&line, &len, nssfp)) != -1) {
+	p = NULL;
+	while (getline(&line, &len, nssfp) != -1) {
 		if (line[0] == '#')
 			continue;
 		if (strlen(line) < 8)
@@ -82,6 +83,9 @@ void nss_init(const char *nsswitch_path) {
 		if (*p != '\0')
 			break;
 	}
+	if (p == NULL) {
+		goto null_subid;
+	}
 	token = strtok_r(p, " \n\t", &saveptr);
 	if (token == NULL) {
 		fprintf(shadow_logfd, "No usable subid NSS module found, using files\n");
-- 
2.47.2