From 700daeecb890721176bd23effc4166221cdd0271 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 4 Mar 2016 10:17:17 +0000
Subject: [PATCH] Avoid overflow in EVP_EncodeUpdate

An overflow can occur in the EVP_EncodeUpdate function which is used for
Base64 encoding of binary data. If an attacker is able to supply very large
amounts of input data then a length check can overflow resulting in a heap
corruption. Due to the very large amounts of data involved this will most
likely result in a crash.

Internally to OpenSSL the EVP_EncodeUpdate function is primarly used by the
PEM_write_bio* family of functions. These are mainly used within the
OpenSSL command line applications, so any application which processes
data from an untrusted source and outputs it as a PEM file should be
considered vulnerable to this issue.

User applications that call these APIs directly with large amounts of
untrusted data may also be vulnerable.

Issue reported by Guido Vranken.

CVE-2016-2105
---
 crypto/evp/encode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

From 29188216f818e5b34f3b17ee8ed31e8336f3817e Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Mon, 25 Apr 2016 09:06:29 +0100
Subject: [PATCH] Ensure EVP_EncodeUpdate handles an output length that is too long

With the EVP_EncodeUpdate function it is the caller's responsibility to
determine how big the output buffer should be. The function writes the
amount actually used to |*outl|. However this could go negative with a
sufficiently large value for |inl|. We add a check for this error
condition.

From f332816ef87556b7e89b98206c14df1f128b6d9f Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Mon, 25 Apr 2016 11:54:30 +0100
Subject: [PATCH] Add documentation for EVP_EncodeInit() and similar functions

Index: openssl-0.9.7g/crypto/evp/encode.c
===================================================================
--- openssl-0.9.7g.orig/crypto/evp/encode.c	2016-04-30 12:21:13.045044374 +0200
+++ openssl-0.9.7g/crypto/evp/encode.c	2016-04-30 12:22:16.700998586 +0200
@@ -132,12 +132,12 @@ void EVP_EncodeUpdate(EVP_ENCODE_CTX *ct
 	     unsigned char *in, int inl)
 	{
 	int i,j;
-	unsigned int total=0;
+	size_t total=0;
 
 	*outl=0;
 	if (inl == 0) return;
 	OPENSSL_assert(ctx->length <= sizeof ctx->enc_data);
-	if ((ctx->num+inl) < ctx->length)
+	if (ctx->length - ctx->num > inl)
 		{
 		memcpy(&(ctx->enc_data[ctx->num]),in,inl);
 		ctx->num+=inl;
@@ -156,7 +156,7 @@ void EVP_EncodeUpdate(EVP_ENCODE_CTX *ct
 		*out='\0';
 		total=j+1;
 		}
-	while (inl >= ctx->length)
+	while (inl >= ctx->length && total <= INT_MAX)
 		{
 		j=EVP_EncodeBlock(out,in,ctx->length);
 		in+=ctx->length;
@@ -166,6 +166,11 @@ void EVP_EncodeUpdate(EVP_ENCODE_CTX *ct
 		*out='\0';
 		total+=j+1;
 		}
+	if (total > INT_MAX) {
+	    /* Too much output data! */
+	    *outl = 0;
+	    return;
+	}
 	if (inl != 0)
 		memcpy(&(ctx->enc_data[0]),in,inl);
 	ctx->num=inl;
Index: openssl-0.9.7g/doc/crypto/EVP_EncodeInit.pod
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ openssl-0.9.7g/doc/crypto/EVP_EncodeInit.pod	2016-04-30 12:21:24.149210824 +0200
@@ -0,0 +1,145 @@
+=pod
+
+=head1 NAME
+
+EVP_ENCODE_CTX_new, EVP_ENCODE_CTX_free, EVP_ENCODE_CTX_num, EVP_EncodeInit,
+EVP_EncodeUpdate, EVP_EncodeFinal, EVP_EncodeBlock, EVP_DecodeInit,
+EVP_DecodeUpdate, EVP_DecodeFinal, EVP_DecodeBlock - EVP base 64 encode/decode
+routines
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ EVP_ENCODE_CTX *EVP_ENCODE_CTX_new(void);
+ void EVP_ENCODE_CTX_free(EVP_ENCODE_CTX *ctx);
+ int EVP_ENCODE_CTX_num(EVP_ENCODE_CTX *ctx);
+ void EVP_EncodeInit(EVP_ENCODE_CTX *ctx);
+ void EVP_EncodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,
+                       const unsigned char *in, int inl);
+ void EVP_EncodeFinal(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl);
+ int EVP_EncodeBlock(unsigned char *t, const unsigned char *f, int n);
+
+ void EVP_DecodeInit(EVP_ENCODE_CTX *ctx);
+ int EVP_DecodeUpdate(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl,
+                      const unsigned char *in, int inl);
+ int EVP_DecodeFinal(EVP_ENCODE_CTX *ctx, unsigned
+                     char *out, int *outl);
+ int EVP_DecodeBlock(unsigned char *t, const unsigned char *f, int n);
+
+=head1 DESCRIPTION
+
+The EVP encode routines provide a high level interface to base 64 encoding and
+decoding. Base 64 encoding converts binary data into a printable form that uses
+the characters A-Z, a-z, 0-9, "+" and "/" to represent the data. For every 3
+bytes of binary data provided approximately 4 bytes of base 64 encoded data will
+be produced (see below). If the input data length is not a multiple of 3 then
+the output data will be padded at the end using the "=" character.
+
+EVP_ENCODE_CTX_new() allocates, initializes and returns a context to be used for
+the encode/decode functions.
+
+EVP_ENCODE_CTX_free() cleans up an encode/decode context B<ctx> and frees up the
+space allocated to it.
+
+Encoding of binary base 64 data is performed in blocks of 48 input bytes (or
+less for the final block). For each 48 byte input block encoded 64 bytes of base
+64 data is output plus an additional newline character (i.e. 65 bytes in total).
+The final block (which may be less than 48 bytes) will output 4 bytes for every
+3 bytes of input. If the data length is not divisible by 3 then a full 4 bytes
+is still output for the final 1 or 2 bytes of input. Similarly a newline
+character will also be output.
+
+EVP_EncodeInit() initialises B<ctx> for the start of a new encoding operation.
+
+EVP_EncodeUpdate() encode B<inl> bytes of data found in the buffer pointed to by
+B<in>. The output is stored in the buffer B<out> and the number of bytes output
+is stored in B<*outl>. It is the caller's responsibility to ensure that the
+buffer at B<out> is sufficiently large to accommodate the output data. Only full
+blocks of data (48 bytes) will be immediately processed and output by this
+function. Any remainder is held in the B<ctx> object and will be processed by a
+subsequent call to EVP_EncodeUpdate() or EVP_EncodeFinal(). To calculate the
+required size of the output buffer add together the value of B<inl> with the
+amount of unprocessed data held in B<ctx> and divide the result by 48 (ignore
+any remainder). This gives the number of blocks of data that will be processed.
+Ensure the output buffer contains 65 bytes of storage for each block, plus an
+additional byte for a NUL terminator. EVP_EncodeUpdate() may be called
+repeatedly to process large amounts of input data. In the event of an error
+EVP_EncodeUpdate() will set B<*outl> to 0.
+
+EVP_EncodeFinal() must be called at the end of an encoding operation. It will
+process any partial block of data remaining in the B<ctx> object. The output
+data will be stored in B<out> and the length of the data written will be stored
+in B<*outl>. It is the caller's responsibility to ensure that B<out> is
+sufficiently large to accommodate the output data which will never be more than
+65 bytes plus an additional NUL terminator (i.e. 66 bytes in total).
+
+EVP_ENCODE_CTX_num() will return the number of as yet unprocessed bytes still to
+be encoded or decoded that are pending in the B<ctx> object.
+
+EVP_EncodeBlock() encodes a full block of input data in B<f> and of length
+B<dlen> and stores it in B<t>. For every 3 bytes of input provided 4 bytes of
+output data will be produced. If B<dlen> is not divisible by 3 then the block is
+encoded as a final block of data and the output is padded such that it is always
+divisible by 4. Additionally a NUL terminator character will be added. For
+example if 16 bytes of input data is provided then 24 bytes of encoded data is
+created plus 1 byte for a NUL terminator (i.e. 25 bytes in total). The length of
+the data generated I<without> the NUL terminator is returned from the function.
+
+EVP_DecodeInit() initialises B<ctx> for the start of a new decoding operation.
+
+EVP_DecodeUpdate() decodes B<inl> bytes of data found in the buffer pointed to
+by B<in>. The output is stored in the buffer B<out> and the number of bytes
+output is stored in B<*outl>. It is the caller's responsibility to ensure that
+the buffer at B<out> is sufficiently large to accommodate the output data. This
+function will attempt to decode as much data as possible in 4 byte chunks. Any
+whitespace, newline or carriage return characters are ignored. Any partial chunk
+of unprocessed data (1, 2 or 3 bytes) that remains at the end will be held in
+the B<ctx> object and processed by a subsequent call to EVP_DecodeUpdate(). If
+any illegal base 64 characters are encountered or if the base 64 padding
+character "=" is encountered in the middle of the data then the function returns
+-1 to indicate an error. A return value of 0 or 1 indicates successful
+processing of the data. A return value of 0 additionally indicates that the last
+input data characters processed included the base 64 padding character "=" and
+therefore no more non-padding character data is expected to be processed. For
+every 4 valid base 64 bytes processed (ignoring whitespace, carriage returns and
+line feeds), 3 bytes of binary output data will be produced (or less at the end
+of the data where the padding character "=" has been used).
+
+EVP_DecodeFinal() must be called at the end of a decoding operation. If there
+is any unprocessed data still in B<ctx> then the input data must not have been
+a multiple of 4 and therefore an error has occurred. The function will return -1
+in this case. Otherwise the function returns 1 on success.
+
+EVP_DecodeBlock() will decode the block of B<n> bytes of base 64 data contained
+in B<f> and store the result in B<t>. Any leading whitespace will be trimmed as
+will any trailing whitespace, newlines, carriage returns or EOF characters.
+After such trimming the length of the data in B<f> must be divisbile by 4. For
+every 4 input bytes exactly 3 output bytes will be produced. The output will be
+padded with 0 bits if necessary to ensure that the output is always 3 bytes for
+every 4 input bytes. This function will return the length of the data decoded or
+-1 on error.
+
+=head1 RETURN VALUES
+
+EVP_ENCODE_CTX_new() returns a pointer to the newly allocated EVP_ENCODE_CTX
+object or NULL on error.
+
+EVP_ENCODE_CTX_num() returns the number of bytes pending encoding or decoding in
+B<ctx>.
+
+EVP_EncodeBlock() returns the number of bytes encoded excluding the NUL
+terminator.
+
+EVP_DecodeUpdate() returns -1 on error and 0 or 1 on success. If 0 is returned
+then no more non-padding base 64 characters are expected.
+
+EVP_DecodeFinal() returns -1 on error or 1 on success.
+
+EVP_DecodeBlock() returns the length of the data decoded or -1 on error.
+
+=head1 SEE ALSO
+
+L<evp(3)>
+
+=cut
Index: openssl-0.9.7g/doc/crypto/evp.pod
===================================================================
--- openssl-0.9.7g.orig/doc/crypto/evp.pod	2016-04-30 12:21:13.046044390 +0200
+++ openssl-0.9.7g/doc/crypto/evp.pod	2016-04-30 12:21:24.149210824 +0200
@@ -24,6 +24,10 @@ functions.  The B<EVP_Digest>I<...> func
 
 Algorithms are loaded with OpenSSL_add_all_algorithms(3).
 
+The L<B<EVP_Encode>I<...>|EVP_EncodeInit(3)> and
+L<B<EVP_Decode>I<...>|EVP_EncodeInit(3)> functions implement base 64 encoding
+and decoding.
+
 All the symmetric algorithms (ciphers) and digests can be replaced by ENGINE
 modules providing alternative implementations. If ENGINE implementations of
 ciphers or digests are registered as defaults, then the various EVP functions
@@ -39,6 +43,7 @@ L<EVP_OpenInit(3)|EVP_OpenInit(3)>,
 L<EVP_SealInit(3)|EVP_SealInit(3)>,
 L<EVP_SignInit(3)|EVP_SignInit(3)>,
 L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>,
+L<EVP_EncodeInit(3)>,
 L<OpenSSL_add_all_algorithms(3)|OpenSSL_add_all_algorithms(3)>,
 L<engine(3)|engine(3)>
 
