From: Jeremy Allison <jra@samba.org>
Date: Fri, 15 May 2020 19:18:02 +0000 (-0700)
Subject: s3: lib: Paranoia around use of snprintf copying into a fixed-size buffer from a... 
X-Git-Tag: samba-4.10.16~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=55a3861260c4146607675f1fcaac7054670ee0a5;p=thirdparty%2Fsamba.git

s3: lib: Paranoia around use of snprintf copying into a fixed-size buffer from a getenv() pointer.

Post checks for overflow/error.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Mon May 18 23:42:57 UTC 2020 on sn-devel-184

(cherry picked from commit dd1f750293ef4361455a5d5b63fc7a89495715b7)

Autobuild-User(v4-10-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-10-test): Fri May 22 16:07:51 UTC 2020 on sn-devel-144
---

diff --git a/lib/util/util_paths.c b/lib/util/util_paths.c
index c05246a7407..c0ee5c32c30 100644
--- a/lib/util/util_paths.c
+++ b/lib/util/util_paths.c
@@ -73,12 +73,16 @@ static char *get_user_home_dir(TALLOC_CTX *mem_ctx)
 
 	rc = getpwuid_r(getuid(), &pwd, buf, NSS_BUFLEN_PASSWD, &pwdbuf);
 	if (rc != 0 || pwdbuf == NULL ) {
+		int len_written;
 		const char *szPath = getenv("HOME");
 		if (szPath == NULL) {
 			return NULL;
 		}
-		snprintf(buf, sizeof(buf), "%s", szPath);
-
+		len_written = snprintf(buf, sizeof(buf), "%s", szPath);
+		if (len_written >= sizeof(buf) || len_written < 0) {
+			/* Output was truncated or an error. */
+			return NULL;
+		}
 		return talloc_strdup(mem_ctx, buf);
 	}