2 files changed, 20 insertions, 7 deletions
diff --git a/crypto/buffer/buf_str.c b/crypto/buffer/buf_str.c
index fdde3d7db4ba..233af246e4c5 100644
--- a/crypto/buffer/buf_str.c
+++ b/crypto/buffer/buf_str.c
@@ -58,12 +58,13 @@
 
 #include <stdio.h>
 #include "cryptlib.h"
+#include <limits.h>
 #include <openssl/buffer.h>
 
 char *BUF_strdup(const char *str)
 {
     if (str == NULL)
-        return (NULL);
+        return NULL;
     return BUF_strndup(str, strlen(str));
 }
 
@@ -72,14 +73,20 @@ char *BUF_strndup(const char *str, size_t siz)
     char *ret;
 
     if (str == NULL)
-        return (NULL);
+        return NULL;
+
+    if (siz >= INT_MAX)
+        return NULL;
 
     ret = OPENSSL_malloc(siz + 1);
     if (ret == NULL) {
         BUFerr(BUF_F_BUF_STRNDUP, ERR_R_MALLOC_FAILURE);
-        return (NULL);
+        return NULL;
     }
-    BUF_strlcpy(ret, str, siz + 1);
+
+    memcpy(ret, str, siz);
+    ret[siz] = '\0';
+
     return (ret);
 }
 
@@ -87,13 +94,13 @@ void *BUF_memdup(const void *data, size_t siz)
 {
     void *ret;
 
-    if (data == NULL)
-        return (NULL);
+    if (data == NULL || siz >= INT_MAX)
+        return NULL;
 
     ret = OPENSSL_malloc(siz);
     if (ret == NULL) {
         BUFerr(BUF_F_BUF_MEMDUP, ERR_R_MALLOC_FAILURE);
-        return (NULL);
+        return NULL;
     }
     return memcpy(ret, data, siz);
 }
diff --git a/crypto/buffer/buffer.h b/crypto/buffer/buffer.h
index 632df93c657c..89183adb4a8e 100644
--- a/crypto/buffer/buffer.h
+++ b/crypto/buffer/buffer.h
@@ -85,7 +85,13 @@ void BUF_MEM_free(BUF_MEM *a);
 int BUF_MEM_grow(BUF_MEM *str, size_t len);
 int BUF_MEM_grow_clean(BUF_MEM *str, size_t len);
 char *BUF_strdup(const char *str);
+
+/*
+ * Like strndup, but in addition, explicitly guarantees to never read past the
+ * first |siz| bytes of |str|.
+ */
 char *BUF_strndup(const char *str, size_t siz);
+
 void *BUF_memdup(const void *data, size_t siz);
 void BUF_reverse(unsigned char *out, const unsigned char *in, size_t siz);