selinux: add __GFP_NOWARN to hashtab_init() allocations

As reported by syzbot, hashtab_init() can be affected by abnormally
large policy loads which would cause the kernel's allocator to emit
a warning in some configurations.  Since the SELinux hashtab_init()
code handles the case where the allocation fails, due to a large
request or some other reason, we can safely add the __GFP_NOWARN flag
to squelch these abnormally large allocation warnings.

Reported-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
Tested-by: syzbot+bc2c99c2929c3d219fb3@syzkaller.appspotmail.com
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: pcmoore

security/selinux/ss/hashtab.c

@@ -40,7 +40,8 @@ int hashtab_init(struct hashtab *h, u32 nel_hint)
 	h->htable = NULL;
 
 	if (size) {
-		h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
+		h->htable = kcalloc(size, sizeof(*h->htable),
+				    GFP_KERNEL | __GFP_NOWARN);
 		if (!h->htable)
 			return -ENOMEM;
 		h->size = size;