[PATCH] selinux: Fix strncpy in libselinux and libsepol

[Richard Haines <richard_c_haines@xxxxxxxxxxxxxx>]

When building with gcc9, get build errors such as:

genbools.c:24:2: error: ‘strncpy’ output may be truncated copying 8191
bytes from a string of length 8191 [-Werror=stringop-truncation]
   24 |  strncpy(dest, ptr, size);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Richard Haines <richard_c_haines@xxxxxxxxxxxxxx>
---
 libselinux/src/booleans.c |  4 ++--
 libsepol/src/genbools.c   | 20 +++++++++++---------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/libselinux/src/booleans.c b/libselinux/src/booleans.c
index ab1e0754..cdc03517 100644
--- a/libselinux/src/booleans.c
+++ b/libselinux/src/booleans.c
@@ -539,7 +539,7 @@ int security_load_booleans(char *path)
 
 	__fsetlocking(boolf, FSETLOCKING_BYCALLER);
 	while (getline(&inbuf, &len, boolf) > 0) {
-		int ret = process_boolean(inbuf, name, sizeof(name), &val);
+		int ret = process_boolean(inbuf, name, len, &val);
 		if (ret == -1)
 			errors++;
 		if (ret == 1)
@@ -557,7 +557,7 @@ int security_load_booleans(char *path)
 		int ret;
 		__fsetlocking(boolf, FSETLOCKING_BYCALLER);
 		while (getline(&inbuf, &len, boolf) > 0) {
-			ret = process_boolean(inbuf, name, sizeof(name), &val);
+			ret = process_boolean(inbuf, name, len, &val);
 			if (ret == -1)
 				errors++;
 			if (ret == 1)
diff --git a/libsepol/src/genbools.c b/libsepol/src/genbools.c
index d4a2df62..ad194ca6 100644
--- a/libsepol/src/genbools.c
+++ b/libsepol/src/genbools.c
@@ -10,6 +10,8 @@
 #include "private.h"
 #include "dso.h"
 
+#define FGET_BUFSIZ 255
+
 /* -- Deprecated -- */
 
 static char *strtrim(char *dest, char *source, int size)
@@ -32,7 +34,7 @@ static char *strtrim(char *dest, char *source, int size)
 
 static int process_boolean(char *buffer, char *name, int namesize, int *val)
 {
-	char name1[BUFSIZ];
+	char name1[FGET_BUFSIZ];
 	char *ptr = NULL;
 	char *tok;
 
@@ -48,7 +50,7 @@ static int process_boolean(char *buffer, char *name, int namesize, int *val)
 		ERR(NULL, "illegal boolean definition %s", buffer);
 		return -1;
 	}
-	strncpy(name1, tok, BUFSIZ - 1);
+	strncpy(name1, tok, FGET_BUFSIZ - 1);
 	strtrim(name, name1, namesize - 1);
 
 	tok = strtok_r(NULL, "\0", &ptr);
@@ -79,8 +81,8 @@ static int load_booleans(struct policydb *policydb, const char *path,
 {
 	FILE *boolf;
 	char *buffer = NULL;
-	char localbools[BUFSIZ];
-	char name[BUFSIZ];
+	char localbools[FGET_BUFSIZ];
+	char name[FGET_BUFSIZ + 1];
 	int val;
 	int errors = 0, changes = 0;
 	struct cond_bool_datum *datum;
@@ -90,12 +92,12 @@ static int load_booleans(struct policydb *policydb, const char *path,
 		goto localbool;
 
 #ifdef __APPLE__
-        if ((buffer = (char *)malloc(255 * sizeof(char))) == NULL) {
-          ERR(NULL, "out of memory");
-	  return -1;
+	if ((buffer = (char *)malloc(FGET_BUFSIZ * sizeof(char))) == NULL) {
+		ERR(NULL, "out of memory");
+		return -1;
 	}
 
-        while(fgets(buffer, 255, boolf) != NULL) {
+	while (fgets(buffer, FGET_BUFSIZ, boolf) != NULL) {
 #else
 	size_t size = 0;
 	while (getline(&buffer, &size, boolf) > 0) {
@@ -124,7 +126,7 @@ static int load_booleans(struct policydb *policydb, const char *path,
 
 #ifdef __APPLE__
 
-	  while(fgets(buffer, 255, boolf) != NULL) {
+	while (fgets(buffer, FGET_BUFSIZ, boolf) != NULL) {
 #else
 
 	    while (getline(&buffer, &size, boolf) > 0) {
-- 
2.21.0