[PATCH 13/23] libsepol: assure string NUL-termination

[Christian Göttsche <cgzones@xxxxxxxxxxxxxx>]

ibendport_record.c: In function ‘sepol_ibendport_get_ibdev_name’:
ibendport_record.c:169:2: error: ‘strncpy’ specified bound 64 equals destination size [-Werror=stringop-truncation]
  169 |  strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ibendport_record.c: In function ‘sepol_ibendport_set_ibdev_name’:
ibendport_record.c:189:2: error: ‘strncpy’ specified bound 64 equals destination size [-Werror=stringop-truncation]
  189 |  strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

strncpy(3) does not NUL-terminate the destination if the source is of
the same length or longer then the specified size.
Reduce the size to copy by 1.

Found by Clang

Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
---
 libsepol/src/ibendport_record.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libsepol/src/ibendport_record.c b/libsepol/src/ibendport_record.c
index adf67161..2eb8ca18 100644
--- a/libsepol/src/ibendport_record.c
+++ b/libsepol/src/ibendport_record.c
@@ -166,7 +166,7 @@ int sepol_ibendport_get_ibdev_name(sepol_handle_t *handle,
 	if (sepol_ibendport_alloc_ibdev_name(handle, &tmp_ibdev_name) < 0)
 		goto err;
 
-	strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX);
+	strncpy(tmp_ibdev_name, ibendport->ibdev_name, IB_DEVICE_NAME_MAX - 1);
 	*ibdev_name = tmp_ibdev_name;
 	return STATUS_SUCCESS;
 
@@ -186,7 +186,7 @@ int sepol_ibendport_set_ibdev_name(sepol_handle_t *handle,
 	if (sepol_ibendport_alloc_ibdev_name(handle, &tmp) < 0)
 		goto err;
 
-	strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX);
+	strncpy(tmp, ibdev_name, IB_DEVICE_NAME_MAX - 1);
 	free(ibendport->ibdev_name);
 	ibendport->ibdev_name = tmp;
 	return STATUS_SUCCESS;
-- 
2.32.0