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Use const size buffer for local output in CCM decryption.

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Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
This commit is contained in:
Mateusz Starzyk 2021-08-09 11:32:11 +02:00
parent c562788068
commit f337850738
2 changed files with 3 additions and 27 deletions
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2
include/mbedtls/ccm.h
View File

@ -61,8 +61,6 @@
#define MBEDTLS_ERR_CCM_BAD_INPUT -0x000D #define MBEDTLS_ERR_CCM_BAD_INPUT -0x000D
/** Authenticated decryption failed. */ /** Authenticated decryption failed. */
#define MBEDTLS_ERR_CCM_AUTH_FAILED -0x000F #define MBEDTLS_ERR_CCM_AUTH_FAILED -0x000F
/** Memory allocation failed */
#define MBEDTLS_ERR_CCM_ALLOC_FAILED -0x0011
#ifdef __cplusplus #ifdef __cplusplus
extern "C" { extern "C" {

28
library/ccm.c
View File

@ -43,9 +43,6 @@
#include <stdio.h> #include <stdio.h>
#define mbedtls_printf printf #define mbedtls_printf printf
#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */ #endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif /* MBEDTLS_PLATFORM_C */ #endif /* MBEDTLS_PLATFORM_C */
#if !defined(MBEDTLS_CCM_ALT) #if !defined(MBEDTLS_CCM_ALT)
@ -337,8 +334,7 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
unsigned char i; unsigned char i;
size_t use_len, offset, olen; size_t use_len, offset, olen;
const size_t local_output_len = input_len; unsigned char local_output[16];
unsigned char* local_output = NULL;
if( ctx->state & CCM_STATE__ERROR ) if( ctx->state & CCM_STATE__ERROR )
{ {
@ -350,19 +346,6 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
return MBEDTLS_ERR_CCM_BAD_INPUT; return MBEDTLS_ERR_CCM_BAD_INPUT;
} }
/* Local output is used for decryption only. */
if( local_output_len > 0 && \
( ctx->mode == MBEDTLS_CCM_DECRYPT || \
ctx->mode == MBEDTLS_CCM_STAR_DECRYPT ) )
{
local_output = mbedtls_calloc( local_output_len, sizeof( *local_output) );
if( local_output == NULL )
{
ctx->state |= CCM_STATE__ERROR;
return MBEDTLS_ERR_CCM_ALLOC_FAILED;
}
}
if( output_size < input_len ) if( output_size < input_len )
return( MBEDTLS_ERR_CCM_BAD_INPUT ); return( MBEDTLS_ERR_CCM_BAD_INPUT );
*output_len = input_len; *output_len = input_len;
@ -414,7 +397,7 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
ctx->y[i + offset] ^= local_output[i]; ctx->y[i + offset] ^= local_output[i];
memcpy( output, local_output, use_len ); memcpy( output, local_output, use_len );
mbedtls_platform_zeroize( local_output, local_output_len ); mbedtls_platform_zeroize( local_output, 16 );
if( use_len + offset == 16 || ctx->processed == ctx->plaintext_len ) if( use_len + offset == 16 || ctx->processed == ctx->plaintext_len )
{ {
@ -439,12 +422,7 @@ int mbedtls_ccm_update( mbedtls_ccm_context *ctx,
} }
exit: exit:
if( ctx->mode == MBEDTLS_CCM_DECRYPT || \ mbedtls_platform_zeroize( local_output, 16 );
ctx->mode == MBEDTLS_CCM_STAR_DECRYPT )
{
mbedtls_platform_zeroize( local_output, local_output_len );
mbedtls_free( local_output );
}
return ret; return ret;
} }