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Fix potential overflow in base64_encode

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Manuel Pégourié-Gonnard 2015-09-30 16:30:28 +02:00
parent 5aff029f9d
commit 48ec2c7b5e
3 changed files with 12 additions and 5 deletions
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3
ChangeLog
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@ -18,6 +18,9 @@ Security
* Fix potential double-free if ssl_set_psk() is called repeatedly on
the same ssl_context object and some memory allocations fail.
Found by Guido Vranken. Can not be forced remotely.
* Fix possible heap buffer overflow in base64_encode() when the input
buffer is 512MB or larger on 32-bit platforms.
Found by Guido Vranken. Not trigerrable remotely in TLS.
= mbed TLS 1.3.13 reladsed 2015-09-17

3
include/polarssl/base64.h
View file

@ -25,6 +25,7 @@
#define POLARSSL_BASE64_H
#include <stddef.h>
#include <limits.h>
#define POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL -0x002A /**< Output buffer too small. */
#define POLARSSL_ERR_BASE64_INVALID_CHARACTER -0x002C /**< Invalid character in input. */
@ -44,6 +45,8 @@ extern "C" {
* \return 0 if successful, or POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL.
* *dlen is always updated to reflect the amount
* of data that has (or would have) been written.
* If that length cannot be represented, then no data is
* written to the buffer and *olen is set to SIZE_T_MAX.
*
* \note Call this function with *dlen = 0 to obtain the
* required buffer size in *dlen

11
library/base64.c
View file

@ -91,15 +91,16 @@ int base64_encode( unsigned char *dst, size_t *dlen,
return( 0 );
}
n = ( slen << 3 ) / 6;
n = slen / 3 + ( slen % 3 != 0 );
switch( ( slen << 3 ) - ( n * 6 ) )
if( n > ( SIZE_T_MAX - 1 ) / 4 )
{
case 2: n += 3; break;
case 4: n += 2; break;
default: break;
*dlen = SIZE_T_MAX;
return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL );
}
n *= 4;
if( *dlen < n + 1 )
{
*dlen = n + 1;