commit a2cefa2: [Minor] Add array allocation methods to handle integer overflow

[Vsevolod Stakhov]

Author: Vsevolod Stakhov
Date: 2022-04-01 18:33:08 +0100
URL: https://github.com/rspamd/rspamd/commit/a2cefa2b675273588b6dd82483b181b9afad88fc

[Minor] Add array allocation methods to handle integer overflow

---
 src/libutil/mem_pool.c | 19 +++++++++++++++++++
 src/libutil/mem_pool.h | 15 +++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/src/libutil/mem_pool.c b/src/libutil/mem_pool.c
index ac0a28e02..d58be5e08 100644
--- a/src/libutil/mem_pool.c
+++ b/src/libutil/mem_pool.c
@@ -559,6 +559,25 @@ rspamd_mempool_alloc_ (rspamd_mempool_t * pool, gsize size, gsize alignment, con
 	return memory_pool_alloc_common (pool, size, alignment, RSPAMD_MEMPOOL_NORMAL, loc);
 }
 
+/*
+ * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
+ * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
+ */
+#define MUL_NO_OVERFLOW	(1UL << (sizeof(gsize) * 4))
+
+void *
+rspamd_mempool_alloc_array_ (rspamd_mempool_t * pool,  gsize nmemb, gsize size, gsize alignment, const gchar *loc)
+{
+	if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+		nmemb > 0 && G_MAXSIZE / nmemb < size) {
+
+		g_error("alloc_array: overflow %"G_GSIZE_FORMAT" * %"G_GSIZE_FORMAT"",
+				nmemb, size);
+		g_abort();
+	}
+	return memory_pool_alloc_common (pool, size, alignment, RSPAMD_MEMPOOL_NORMAL, loc);
+}
+
 void *
 rspamd_mempool_alloc0_ (rspamd_mempool_t * pool, gsize size, gsize alignment, const gchar *loc)
 {
diff --git a/src/libutil/mem_pool.h b/src/libutil/mem_pool.h
index 207f5031b..0ca1d3905 100644
--- a/src/libutil/mem_pool.h
+++ b/src/libutil/mem_pool.h
@@ -154,8 +154,23 @@ rspamd_mempool_t *rspamd_mempool_new_ (gsize size, const gchar *tag, gint flags,
  */
 void *rspamd_mempool_alloc_ (rspamd_mempool_t *pool, gsize size, gsize alignment, const gchar *loc)
 	RSPAMD_ATTR_ALLOC_SIZE(2) RSPAMD_ATTR_ALLOC_ALIGN(MIN_MEM_ALIGNMENT) RSPAMD_ATTR_RETURNS_NONNUL;
+/**
+ * Allocates array handling potential integer overflow
+ * @param pool
+ * @param nmemb
+ * @param size
+ * @param alignment
+ * @param loc
+ * @return
+ */
+void *rspamd_mempool_alloc_array_ (rspamd_mempool_t *pool, gsize nmemb, gsize size, gsize alignment, const gchar *loc)
+RSPAMD_ATTR_ALLOC_SIZE(2) RSPAMD_ATTR_ALLOC_ALIGN(MIN_MEM_ALIGNMENT) RSPAMD_ATTR_RETURNS_NONNUL;
 #define rspamd_mempool_alloc(pool, size) \
 	rspamd_mempool_alloc_((pool), (size), MIN_MEM_ALIGNMENT, (G_STRLOC))
+#define rspamd_mempool_alloc_array(pool, nmemb, size) \
+	rspamd_mempool_alloc_array_((pool), (nmemb), (size), MIN_MEM_ALIGNMENT, (G_STRLOC))
+#define rspamd_mempool_alloc_array_type(pool, nmemb, type) \
+	(type *)rspamd_mempool_alloc_array_((pool), (nmemb), sizeof(type), MIN_MEM_ALIGNMENT, (G_STRLOC))
 #define rspamd_mempool_alloc_type(pool, type) \
 	(type *)(rspamd_mempool_alloc_((pool), sizeof(type), \
 	MAX(MIN_MEM_ALIGNMENT, RSPAMD_ALIGNOF(type)), (G_STRLOC)))