[PATCH] flask: fix gcov build with gcc14+

[Jan Beulich <jbeulich@xxxxxxxx>]

Gcc's "threading" of conditionals can lead to undue warnings, as reported
in e.g. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116519 (no matter
that the overall situation is different there). While my gcc15 complains
("buf[2] may be used uninitialized in this function") about only two of
the three instances (not about the one in type_read()), adjust all three
to be on the safe side.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
While auditing uses of next_entry(), I noticed POLICYDB_VERSION_ROLETRANS
dependent ones in policydb_read(): How come the 4th slot isn't used at all
there (not even checked for being e.g. zero, i.e. holding no useful data)?
Then again other instances can be found where data is read but outright
ignored.

--- a/xen/xsm/flask/ss/policydb.c
+++ b/xen/xsm/flask/ss/policydb.c
@@ -1271,7 +1271,10 @@ static int cf_check role_read(struct pol
     if ( ver >= POLICYDB_VERSION_BOUNDARY )
         rc = next_entry(buf, fp, sizeof(buf[0]) * 3);
     else
+    {
         rc = next_entry(buf, fp, sizeof(buf[0]) * 2);
+        buf[2] = cpu_to_le32(0); /* gcc14 onwards */
+    }
 
     if ( rc < 0 )
         goto bad;
@@ -1342,7 +1345,10 @@ static int cf_check type_read(struct pol
     if ( ver >= POLICYDB_VERSION_BOUNDARY )
         rc = next_entry(buf, fp, sizeof(buf[0]) * 4);
     else
+    {
         rc = next_entry(buf, fp, sizeof(buf[0]) * 3);
+        buf[3] = cpu_to_le32(0); /* gcc14 onwards */
+    }
 
     if ( rc < 0 )
         goto bad;
@@ -1436,7 +1442,10 @@ static int cf_check user_read(struct pol
     if ( ver >= POLICYDB_VERSION_BOUNDARY )
         rc = next_entry(buf, fp, sizeof(buf[0]) * 3);
     else
+    {
         rc = next_entry(buf, fp, sizeof(buf[0]) * 2);
+        buf[2] = cpu_to_le32(0); /* gcc14 onwards */
+    }
 
     if ( rc < 0 )
         goto bad;