Check for potentially exploitable overflows in asn1_d2i_read_bio
[openssl.git] / crypto / buffer / buffer.c
index f4b358bbbd674fab32b11a64ce0aba16b769d76a..52e65dfdfcbb0b287a2cf1f0e8894c69a1a03859 100644 (file)
 #include "cryptlib.h"
 #include <openssl/buffer.h>
 
+/* LIMIT_BEFORE_EXPANSION is the maximum n such that (n+3)/3*4 < 2**31. That
+ * function is applied in several functions in this file and this limit ensures
+ * that the result fits in an int. */
+#define LIMIT_BEFORE_EXPANSION 0x5ffffffc
+
 BUF_MEM *BUF_MEM_new(void)
        {
        BUF_MEM *ret;
@@ -105,6 +110,12 @@ int BUF_MEM_grow(BUF_MEM *str, size_t len)
                str->length=len;
                return(len);
                }
+       /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
+       if (len > LIMIT_BEFORE_EXPANSION)
+               {
+               BUFerr(BUF_F_BUF_MEM_GROW,ERR_R_MALLOC_FAILURE);
+               return 0;
+               }
        n=(len+3)/3*4;
        if (str->data == NULL)
                ret=OPENSSL_malloc(n);
@@ -142,6 +153,12 @@ int BUF_MEM_grow_clean(BUF_MEM *str, size_t len)
                str->length=len;
                return(len);
                }
+       /* This limit is sufficient to ensure (len+3)/3*4 < 2**31 */
+       if (len > LIMIT_BEFORE_EXPANSION)
+               {
+               BUFerr(BUF_F_BUF_MEM_GROW,ERR_R_MALLOC_FAILURE);
+               return 0;
+               }
        n=(len+3)/3*4;
        if (str->data == NULL)
                ret=OPENSSL_malloc(n);