From 2f08f676dcbaf27ff5ce69f59d73f8799b3afee8 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Tue, 4 May 2021 14:11:39 +0200
Subject: [PATCH] cpu/esp_common: fix possible overflow in calloc
 implementation

---
 cpu/esp_common/syscalls.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cpu/esp_common/syscalls.c b/cpu/esp_common/syscalls.c
index d09f757bad..9bc337dc61 100644
--- a/cpu/esp_common/syscalls.c
+++ b/cpu/esp_common/syscalls.c
@@ -276,9 +276,13 @@ void* IRAM_ATTR __wrap__realloc_r(struct _reent *r, void* ptr, size_t size)
 
 void* IRAM_ATTR __wrap__calloc_r(struct _reent *r, size_t count, size_t size)
 {
-    void *result = heap_caps_malloc_default(count * size);
+    size_t size_total;
+    if (__builtin_mul_overflow(count, size, &size_total)) {
+        return NULL;
+    }
+    void *result = heap_caps_malloc_default(size_total);
     if (result) {
-        bzero(result, count * size);
+        bzero(result, size_total);
     }
     return result;
 }