[PATCH] libsepol/cil: silence GCC 12 array-bounds false positive

[Christian Göttsche <cgzones@xxxxxxxxxxxxxx>]

GCC 12 produces an array-bounds warning:

    In file included from ../include/sepol/policydb/context.h:23,
                     from ../include/sepol/policydb/policydb.h:62,
                     from ../cil/src/cil_binary.c:41:
    In function ‘mls_level_init’,
        inlined from ‘mls_level_destroy’ at ../include/sepol/policydb/mls_types.h:99:2,
        inlined from ‘mls_level_destroy’ at ../include/sepol/policydb/mls_types.h:92:20,
        inlined from ‘mls_range_destroy’ at ../include/sepol/policydb/mls_types.h:149:2,
        inlined from ‘cil_rangetransition_to_policydb’ at ../cil/src/cil_binary.c:3231:6:
    ../include/sepol/policydb/mls_types.h:89:9: error: ‘memset’ offset [0, 23] is out of the bounds [0, 0] [-Werror=array-bounds]
       89 |         memset(level, 0, sizeof(mls_level_t));
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ../include/sepol/policydb/mls_types.h:89:9: error: ‘memset’ offset [0, 23] is out of the bounds [0, 0] [-Werror=array-bounds]
    cc1: all warnings being treated as errors

This is a false positive, by inspecting the code and compiling with -O3
and -flto.

Closes: https://github.com/SELinuxProject/selinux/issues/339

Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
---
 libsepol/cil/src/cil_binary.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libsepol/cil/src/cil_binary.c b/libsepol/cil/src/cil_binary.c
index 53017e2d..d5211f69 100644
--- a/libsepol/cil/src/cil_binary.c
+++ b/libsepol/cil/src/cil_binary.c
@@ -3222,7 +3222,16 @@ int cil_rangetransition_to_policydb(policydb_t *pdb, const struct cil_db *db, st
 					} else {
 						cil_log(CIL_ERR, "Out of memory\n");
 					}
+// TODO: add upper version bound once fixed in upstream GCC
+#if defined(__GNUC__) && (__GNUC__ >= 12)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Warray-bounds"
+# pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
 					mls_range_destroy(newdatum);
+#if defined(__GNUC__) && (__GNUC__ >= 12)
+# pragma GCC diagnostic pop
+#endif
 					free(newdatum);
 					free(newkey);
 					if (rc != SEPOL_OK) {
-- 
2.35.1