make sure mmap'd memory is page aligned; allocate an additional page …

…for overflow protection
xorpse · Dec 15, 2020 · bda7d2b · bda7d2b
1 parent ead6ced
commit bda7d2b
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Showing 2 changed files with 18 additions and 6 deletions.
diff --git a/src/misc/memory_pool.h b/src/misc/memory_pool.h
@@ -10,10 +10,16 @@ struct memory_pool
 
 bool memory_pool_init(struct memory_pool *pool, uint64_t size)
 {
+    uint64_t pa_size = size + (size % PAGE_SIZE);
+
     pool->used = 0;
-    pool->size = size;
-    pool->memory = mmap(0, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
-    return pool->memory != NULL;
+    pool->size = pa_size;
+    pool->memory = mmap(0, pa_size + PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
+
+    bool result = pool->memory != MAP_FAILED;
+    if (result) mprotect(pool->memory + pa_size, PAGE_SIZE, PROT_NONE);
+
+    return result;
 }
 
 void *memory_pool_push(struct memory_pool *pool, uint64_t size)

diff --git a/src/misc/ts.h b/src/misc/ts.h
@@ -9,10 +9,16 @@ static struct {
 
 bool ts_init(uint64_t size)
 {
+    uint64_t pa_size = size + (size % PAGE_SIZE);
+
     g_temp_storage.used = 0;
-    g_temp_storage.size = size;
-    g_temp_storage.memory = mmap(0, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
-    return g_temp_storage.memory != NULL;
+    g_temp_storage.size = pa_size;
+    g_temp_storage.memory = mmap(0, pa_size + PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
+
+    bool result = g_temp_storage.memory != MAP_FAILED;
+    if (result) mprotect(g_temp_storage.memory + pa_size, PAGE_SIZE, PROT_NONE);
+
+    return result;
 }
 
 void *ts_alloc(uint64_t size)