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From 9310d45087ae546e27e61ddf8f6367f29848220d Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Thu, 22 Mar 2018 10:05:40 +0000
Subject: [PATCH] Limit ASN.1 constructed types recursive definition depth
Constructed types with a recursive definition (such as can be found in
PKCS7) could eventually exceed the stack given malicious input with
excessive recursion. Therefore we limit the stack depth.
CVE-2018-0739
Upstream-Status: Backport [https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=9310d45087ae546e27e61ddf8f6367f29848220d]
Credit to OSSFuzz for finding this issue.
Reviewed-by: Rich Salz <rsalz@openssl.org>
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
crypto/asn1/asn1.h | 1 +
crypto/asn1/asn1_err.c | 3 ++-
crypto/asn1/tasn_dec.c | 62 +++++++++++++++++++++++++++++++++-----------------
3 files changed, 44 insertions(+), 22 deletions(-)
diff --git a/crypto/asn1/asn1.h b/crypto/asn1/asn1.h
index 68e791f..35a2b2a 100644
--- a/crypto/asn1/asn1.h
+++ b/crypto/asn1/asn1.h
@@ -1365,6 +1365,7 @@ void ERR_load_ASN1_strings(void);
# define ASN1_R_MSTRING_NOT_UNIVERSAL 139
# define ASN1_R_MSTRING_WRONG_TAG 140
# define ASN1_R_NESTED_ASN1_STRING 197
+# define ASN1_R_NESTED_TOO_DEEP 219
# define ASN1_R_NON_HEX_CHARACTERS 141
# define ASN1_R_NOT_ASCII_FORMAT 190
# define ASN1_R_NOT_ENOUGH_DATA 142
diff --git a/crypto/asn1/asn1_err.c b/crypto/asn1/asn1_err.c
index fd4ac8d..cfc1512 100644
--- a/crypto/asn1/asn1_err.c
+++ b/crypto/asn1/asn1_err.c
@@ -1,6 +1,6 @@
/* crypto/asn1/asn1_err.c */
/* ====================================================================
- * Copyright (c) 1999-2014 The OpenSSL Project. All rights reserved.
+ * Copyright (c) 1999-2018 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -279,6 +279,7 @@ static ERR_STRING_DATA ASN1_str_reasons[] = {
{ERR_REASON(ASN1_R_MSTRING_NOT_UNIVERSAL), "mstring not universal"},
{ERR_REASON(ASN1_R_MSTRING_WRONG_TAG), "mstring wrong tag"},
{ERR_REASON(ASN1_R_NESTED_ASN1_STRING), "nested asn1 string"},
+ {ERR_REASON(ASN1_R_NESTED_TOO_DEEP), "nested too deep"},
{ERR_REASON(ASN1_R_NON_HEX_CHARACTERS), "non hex characters"},
{ERR_REASON(ASN1_R_NOT_ASCII_FORMAT), "not ascii format"},
{ERR_REASON(ASN1_R_NOT_ENOUGH_DATA), "not enough data"},
diff --git a/crypto/asn1/tasn_dec.c b/crypto/asn1/tasn_dec.c
index d49a5d5..78126e9 100644
--- a/crypto/asn1/tasn_dec.c
+++ b/crypto/asn1/tasn_dec.c
@@ -65,6 +65,14 @@
#include <openssl/buffer.h>
#include <openssl/err.h>
+/*
+ * Constructed types with a recursive definition (such as can be found in PKCS7)
+ * could eventually exceed the stack given malicious input with excessive
+ * recursion. Therefore we limit the stack depth. This is the maximum number of
+ * recursive invocations of asn1_item_embed_d2i().
+ */
+#define ASN1_MAX_CONSTRUCTED_NEST 30
+
static int asn1_check_eoc(const unsigned char **in, long len);
static int asn1_find_end(const unsigned char **in, long len, char inf);
@@ -81,11 +89,11 @@ static int asn1_check_tlen(long *olen, int *otag, unsigned char *oclass,
static int asn1_template_ex_d2i(ASN1_VALUE **pval,
const unsigned char **in, long len,
const ASN1_TEMPLATE *tt, char opt,
- ASN1_TLC *ctx);
+ ASN1_TLC *ctx, int depth);
static int asn1_template_noexp_d2i(ASN1_VALUE **val,
const unsigned char **in, long len,
const ASN1_TEMPLATE *tt, char opt,
- ASN1_TLC *ctx);
+ ASN1_TLC *ctx, int depth);
static int asn1_d2i_ex_primitive(ASN1_VALUE **pval,
const unsigned char **in, long len,
const ASN1_ITEM *it,
@@ -154,17 +162,16 @@ int ASN1_template_d2i(ASN1_VALUE **pval,
{
ASN1_TLC c;
asn1_tlc_clear_nc(&c);
- return asn1_template_ex_d2i(pval, in, len, tt, 0, &c);
+ return asn1_template_ex_d2i(pval, in, len, tt, 0, &c, 0);
}
/*
* Decode an item, taking care of IMPLICIT tagging, if any. If 'opt' set and
* tag mismatch return -1 to handle OPTIONAL
*/
-
-int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
- const ASN1_ITEM *it,
- int tag, int aclass, char opt, ASN1_TLC *ctx)
+static int asn1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in,
+ long len, const ASN1_ITEM *it, int tag, int aclass,
+ char opt, ASN1_TLC *ctx, int depth)
{
const ASN1_TEMPLATE *tt, *errtt = NULL;
const ASN1_COMPAT_FUNCS *cf;
@@ -189,6 +196,11 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
else
asn1_cb = 0;
+ if (++depth > ASN1_MAX_CONSTRUCTED_NEST) {
+ ASN1err(ASN1_F_ASN1_ITEM_EX_D2I, ASN1_R_NESTED_TOO_DEEP);
+ goto err;
+ }
+
switch (it->itype) {
case ASN1_ITYPE_PRIMITIVE:
if (it->templates) {
@@ -204,7 +216,7 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
goto err;
}
return asn1_template_ex_d2i(pval, in, len,
- it->templates, opt, ctx);
+ it->templates, opt, ctx, depth);
}
return asn1_d2i_ex_primitive(pval, in, len, it,
tag, aclass, opt, ctx);
@@ -326,7 +338,7 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
/*
* We mark field as OPTIONAL so its absence can be recognised.
*/
- ret = asn1_template_ex_d2i(pchptr, &p, len, tt, 1, ctx);
+ ret = asn1_template_ex_d2i(pchptr, &p, len, tt, 1, ctx, depth);
/* If field not present, try the next one */
if (ret == -1)
continue;
@@ -444,7 +456,8 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
* attempt to read in field, allowing each to be OPTIONAL
*/
- ret = asn1_template_ex_d2i(pseqval, &p, len, seqtt, isopt, ctx);
+ ret = asn1_template_ex_d2i(pseqval, &p, len, seqtt, isopt, ctx,
+ depth);
if (!ret) {
errtt = seqtt;
goto err;
@@ -514,6 +527,13 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
return 0;
}
+int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
+ const ASN1_ITEM *it,
+ int tag, int aclass, char opt, ASN1_TLC *ctx)
+{
+ return asn1_item_ex_d2i(pval, in, len, it, tag, aclass, opt, ctx, 0);
+}
+
/*
* Templates are handled with two separate functions. One handles any
* EXPLICIT tag and the other handles the rest.
@@ -522,7 +542,7 @@ int ASN1_item_ex_d2i(ASN1_VALUE **pval, const unsigned char **in, long len,
static int asn1_template_ex_d2i(ASN1_VALUE **val,
const unsigned char **in, long inlen,
const ASN1_TEMPLATE *tt, char opt,
- ASN1_TLC *ctx)
+ ASN1_TLC *ctx, int depth)
{
int flags, aclass;
int ret;
@@ -557,7 +577,7 @@ static int asn1_template_ex_d2i(ASN1_VALUE **val,
return 0;
}
/* We've found the field so it can't be OPTIONAL now */
- ret = asn1_template_noexp_d2i(val, &p, len, tt, 0, ctx);
+ ret = asn1_template_noexp_d2i(val, &p, len, tt, 0, ctx, depth);
if (!ret) {
ASN1err(ASN1_F_ASN1_TEMPLATE_EX_D2I, ERR_R_NESTED_ASN1_ERROR);
return 0;
@@ -581,7 +601,7 @@ static int asn1_template_ex_d2i(ASN1_VALUE **val,
}
}
} else
- return asn1_template_noexp_d2i(val, in, inlen, tt, opt, ctx);
+ return asn1_template_noexp_d2i(val, in, inlen, tt, opt, ctx, depth);
*in = p;
return 1;
@@ -594,7 +614,7 @@ static int asn1_template_ex_d2i(ASN1_VALUE **val,
static int asn1_template_noexp_d2i(ASN1_VALUE **val,
const unsigned char **in, long len,
const ASN1_TEMPLATE *tt, char opt,
- ASN1_TLC *ctx)
+ ASN1_TLC *ctx, int depth)
{
int flags, aclass;
int ret;
@@ -665,8 +685,8 @@ static int asn1_template_noexp_d2i(ASN1_VALUE **val,
break;
}
skfield = NULL;
- if (!ASN1_item_ex_d2i(&skfield, &p, len,
- ASN1_ITEM_ptr(tt->item), -1, 0, 0, ctx)) {
+ if (!asn1_item_ex_d2i(&skfield, &p, len, ASN1_ITEM_ptr(tt->item),
+ -1, 0, 0, ctx, depth)) {
ASN1err(ASN1_F_ASN1_TEMPLATE_NOEXP_D2I,
ERR_R_NESTED_ASN1_ERROR);
goto err;
@@ -684,9 +704,8 @@ static int asn1_template_noexp_d2i(ASN1_VALUE **val,
}
} else if (flags & ASN1_TFLG_IMPTAG) {
/* IMPLICIT tagging */
- ret = ASN1_item_ex_d2i(val, &p, len,
- ASN1_ITEM_ptr(tt->item), tt->tag, aclass, opt,
- ctx);
+ ret = asn1_item_ex_d2i(val, &p, len, ASN1_ITEM_ptr(tt->item), tt->tag,
+ aclass, opt, ctx, depth);
if (!ret) {
ASN1err(ASN1_F_ASN1_TEMPLATE_NOEXP_D2I, ERR_R_NESTED_ASN1_ERROR);
goto err;
@@ -694,8 +713,9 @@ static int asn1_template_noexp_d2i(ASN1_VALUE **val,
return -1;
} else {
/* Nothing special */
- ret = ASN1_item_ex_d2i(val, &p, len, ASN1_ITEM_ptr(tt->item),
- -1, tt->flags & ASN1_TFLG_COMBINE, opt, ctx);
+ ret = asn1_item_ex_d2i(val, &p, len, ASN1_ITEM_ptr(tt->item),
+ -1, tt->flags & ASN1_TFLG_COMBINE, opt, ctx,
+ depth);
if (!ret) {
ASN1err(ASN1_F_ASN1_TEMPLATE_NOEXP_D2I, ERR_R_NESTED_ASN1_ERROR);
goto err;
--
1.9.1
|
