Thread (32 messages) 32 messages, 4 authors, 2018-03-06

Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var

From: J Freyensee <hidden>
Date: 2018-03-06 17:05:00
Also in: linux-security-module, lkml

  
+#ifdef CONFIG_PROTECTABLE_MEMORY
+void lkdtm_WRITE_RO_PMALLOC(void)
+{
+	struct gen_pool *pool;
+	int *i;
+
+	pool = pmalloc_create_pool("pool", 0);
+	if (unlikely(!pool)) {
+		pr_info("Failed preparing pool for pmalloc test.");
+		return;
+	}
+
+	i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL);
+	if (unlikely(!i)) {
+		pr_info("Failed allocating memory for pmalloc test.");
+		pmalloc_destroy_pool(pool);
+		return;
+	}
+
+	*i = INT_MAX;
+	pmalloc_protect_pool(pool);
+
+	pr_info("attempting bad pmalloc write at %p\n", i);
+	*i = 0;
Seems harmless, but I don't get why *i local variable needs to be set to 
0 at the end of this function.


Otherwise,

Reviewed-by: Jay Freyensee <redacted>

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