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Fix corner case uses of memory_buffer_alloc.c

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The corner cases fixed include:
    * Allocating a buffer of size 0. With this change, the allocator now
      returns a NULL pointer in this case. Note that changes in pem.c and
      x509_crl.c were required to fix tests that did not work under this
      assumption.
    * Initialising the allocator with less memory than required for headers.
    * Fix header chain checks for uninitialised allocator.
This commit is contained in:
Andres AG 2017-01-30 14:34:25 +00:00 • committed by Andres Amaya Garcia
parent d1a26f19c9
commit 9cf1f96a7b
4 changed files with 24 additions and 15 deletions
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29
library/memory_buffer_alloc.c
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@ -182,9 +182,9 @@ static int verify_header( memory_header *hdr )
static int verify_chain()
{
memory_header *prv = heap.first, *cur = heap.first->next;
memory_header *prv = heap.first, *cur;
if( verify_header( heap.first ) != 0 )
if( heap.first == NULL || verify_header( heap.first ) != 0 )
{
#if defined(MBEDTLS_MEMORY_DEBUG)
mbedtls_fprintf( stderr, "FATAL: verification of first header "
@ -202,6 +202,8 @@ static int verify_chain()
return( 1 );
}
cur = heap.first->next;
while( cur != NULL )
{
if( verify_header( cur ) != 0 )
@ -245,7 +247,9 @@ static void *buffer_alloc_calloc( size_t n, size_t size )
original_len = len = n * size;
if( n != 0 && len / n != size )
if( n == 0 || size == 0 || len / n != size )
return( NULL );
else if( len > (size_t)-MBEDTLS_MEMORY_ALIGN_MULTIPLE )
return( NULL );
if( len % MBEDTLS_MEMORY_ALIGN_MULTIPLE )
@ -386,7 +390,7 @@ static void buffer_alloc_free( void *ptr )
if( ptr == NULL || heap.buf == NULL || heap.first == NULL )
return;
if( p < heap.buf || p > heap.buf + heap.len )
if( p < heap.buf || p >= heap.buf + heap.len )
{
#if defined(MBEDTLS_MEMORY_DEBUG)
mbedtls_fprintf( stderr, "FATAL: mbedtls_free() outside of managed "
@ -570,8 +574,7 @@ static void buffer_alloc_free_mutexed( void *ptr )
void mbedtls_memory_buffer_alloc_init( unsigned char *buf, size_t len )
{
memset( &heap, 0, sizeof(buffer_alloc_ctx) );
memset( buf, 0, len );
memset( &heap, 0, sizeof( buffer_alloc_ctx ) );
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &heap.mutex );
@ -581,20 +584,24 @@ void mbedtls_memory_buffer_alloc_init( unsigned char *buf, size_t len )
mbedtls_platform_set_calloc_free( buffer_alloc_calloc, buffer_alloc_free );
#endif
if( (size_t) buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE )
if( len < sizeof( memory_header ) + MBEDTLS_MEMORY_ALIGN_MULTIPLE )
return;
else if( (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE )
{
/* Adjust len first since buf is used in the computation */
len -= MBEDTLS_MEMORY_ALIGN_MULTIPLE
- (size_t) buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE;
- (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE;
buf += MBEDTLS_MEMORY_ALIGN_MULTIPLE
- (size_t) buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE;
- (size_t)buf % MBEDTLS_MEMORY_ALIGN_MULTIPLE;
}
memset( buf, 0, len );
heap.buf = buf;
heap.len = len;
heap.first = (memory_header *) buf;
heap.first->size = len - sizeof(memory_header);
heap.first = (memory_header *)buf;
heap.first->size = len - sizeof( memory_header );
heap.first->magic1 = MAGIC1;
heap.first->magic2 = MAGIC2;
heap.first_free = heap.first;