Check for potentially exploitable overflows in asn1_d2i_read_bio (564a503b) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP OpenSSL

CHANGES

+9 −0

Original line number	Diff line number	Diff line
		@@ -54,6 +54,15 @@

		Changes between 1.0.1 and 1.0.1a [xx XXX xxxx]

		*) Check for potentially exploitable overflows in asn1_d2i_read_bio
		BUF_mem_grow and BUF_mem_grow_clean. Refuse attempts to shrink buffer
		in CRYPTO_realloc_clean.

		Thanks to Tavis Ormandy, Google Security Team, for discovering this
		issue and to Adam Langley <agl@chromium.org> for fixing it.
		(CVE-2012-2110)
		[Adam Langley (Google), Tavis Ormandy, Google Security Team]

		*) Don't allow TLS 1.2 SHA-256 ciphersuites in TLS 1.0, 1.1 connections.
		[Adam Langley]

crypto/asn1/a_d2i_fp.c

+40 −14

Original line number	Diff line number	Diff line
		@@ -57,6 +57,7 @@
		*/

		#include <stdio.h>
		#include <limits.h>
		#include "cryptlib.h"
		#include <openssl/buffer.h>
		#include <openssl/asn1_mac.h>
		@@ -143,17 +144,11 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		BUF_MEM *b;
		unsigned char *p;
		int i;
		int ret=-1;
		ASN1_const_CTX c;
		int want=HEADER_SIZE;
		size_t want=HEADER_SIZE;
		int eos=0;
		#if defined(__GNUC__) && defined(__ia64)
		/* pathetic compiler bug in all known versions as of Nov. 2002 */
		long off=0;
		#else
		int off=0;
		#endif
		int len=0;
		size_t off=0;
		size_t len=0;

		b=BUF_MEM_new();
		if (b == NULL)
		@@ -169,7 +164,7 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		{
		want-=(len-off);

		if (!BUF_MEM_grow_clean(b,len+want))
		if (len + want < len \|\| !BUF_MEM_grow_clean(b,len+want))
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ERR_R_MALLOC_FAILURE);
		goto err;
		@@ -181,8 +176,15 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		goto err;
		}
		if (i > 0)
		{
		if (len+i < len)
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ASN1_R_TOO_LONG);
		goto err;
		}
		len+=i;
		}
		}
		/* else data already loaded */

		p=(unsigned char *)&(b->data[off]);
		@@ -206,6 +208,11 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		{
		/* no data body so go round again */
		eos++;
		if (eos < 0)
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ASN1_R_HEADER_TOO_LONG);
		goto err;
		}
		want=HEADER_SIZE;
		}
		else if (eos && (c.slen == 0) && (c.tag == V_ASN1_EOC))
		@@ -220,10 +227,16 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		else
		{
		/* suck in c.slen bytes of data */
		want=(int)c.slen;
		want=c.slen;
		if (want > (len-off))
		{
		want-=(len-off);
		if (want > INT_MAX /* BIO_read takes an int length */ \|\|
		len+want < len)
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ASN1_R_TOO_LONG);
		goto err;
		}
		if (!BUF_MEM_grow_clean(b,len+want))
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ERR_R_MALLOC_FAILURE);
		@@ -238,11 +251,18 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		ASN1_R_NOT_ENOUGH_DATA);
		goto err;
		}
		/* This can't overflow because
		* \|len+want\| didn't overflow. */
		len+=i;
		want-=i;
		}
		}
		off+=(int)c.slen;
		if (off + c.slen < off)
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ASN1_R_TOO_LONG);
		goto err;
		}
		off+=c.slen;
		if (eos <= 0)
		{
		break;
		@@ -252,9 +272,15 @@ static int asn1_d2i_read_bio(BIO in, BUF_MEM *pb)
		}
		}

		if (off > INT_MAX)
		{
		ASN1err(ASN1_F_ASN1_D2I_READ_BIO,ASN1_R_TOO_LONG);
		goto err;
		}

		*pb = b;
		return off;
		err:
		if (b != NULL) BUF_MEM_free(b);
		return(ret);
		return -1;
		}

crypto/buffer/buffer.c

+17 −0

Original line number	Diff line number	Diff line
		@@ -60,6 +60,11 @@
		#include "cryptlib.h"
		#include <openssl/buffer.h>

		/* LIMIT_BEFORE_EXPANSION is the maximum n such that (n+3)/34 < 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)/34 < 231 /
		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)/34 < 231 /
		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);

crypto/mem.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -363,6 +363,10 @@ void CRYPTO_realloc_clean(void str, int old_len, int num, const char *file,

		if (num <= 0) return NULL;

		/* We don't support shrinking the buffer. Note the memcpy that copies
		* \|old_len\| bytes to the new buffer, below. */
		if (num < old_len) return NULL;

		if (realloc_debug_func != NULL)
		realloc_debug_func(str, NULL, num, file, line, 0);
		ret=malloc_ex_func(num,file,line);

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