From 1e0c8356f591a62df9725b6c9387da78002ba412 Mon Sep 17 00:00:00 2001 From: Stefan Liebler Date: Tue, 28 Feb 2023 13:37:35 +0100 Subject: nis: Fix stringop-truncation warning with -O3 in nis_local_host. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When building with -O3 on s390x/x86_64, I get this stringop-truncation warning which leads to a build fail: In function ‘nis_local_host’, inlined from ‘nis_local_host’ at nis_local_names.c:147:1: nis_local_names.c:171:11: error: ‘strncpy’ output may be truncated copying between 0 and 1023 bytes from a string of length 1024 [-Werror=stringop-truncation] 171 | strncpy (cp, nis_local_directory (), NIS_MAXNAMELEN - len -1); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We can just ignore this warning as the hostname + '.' + directory-name + '\0' always fits in __nishostname with length of (NIS_MAXNAMELEN + 1) as there is the runtime check above. Furthermore as we already know the length of the directory-name, we can also just use memcpy to copy the directory-name inclusive the NUL-termination. Note: This werror was introduced with commit 32c7acd46401530fdbd4e98508c9baaa705f8b53 "Replace rawmemchr (s, '\0') with strchr" Reviewed-by: Wilco Dijkstra --- nis/nis_local_names.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'nis') diff --git a/nis/nis_local_names.c b/nis/nis_local_names.c index e685255300..699ca04e66 100644 --- a/nis/nis_local_names.c +++ b/nis/nis_local_names.c @@ -161,15 +161,19 @@ nis_local_host (void) if (cp[-1] == '.') return __nishostname; - if (len + strlen (nis_local_directory ()) + 1 > NIS_MAXNAMELEN) + nis_name local_directory = nis_local_directory (); + size_t local_directory_len = strlen (local_directory); + if (len + 1 + local_directory_len > NIS_MAXNAMELEN) { __nishostname[0] = '\0'; return __nishostname; } + /* We have enough space in __nishostname with length of + (NIS_MAXNAMELEN + 1) for + hostname + '.' + directory-name + '\0'. */ *cp++ = '.'; - strncpy (cp, nis_local_directory (), NIS_MAXNAMELEN - len -1); - __nishostname[NIS_MAXNAMELEN] = '\0'; + memcpy (cp, local_directory, local_directory_len + 1); } } -- cgit 1.4.1