Document mutex invariant for HMAC_DRBG

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-02-09 18:43:33 +01:00
parent 05974893e6
commit b5e295d5c9
2 changed files with 10 additions and 0 deletions

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@ -128,6 +128,14 @@ typedef struct mbedtls_hmac_drbg_context
void *p_entropy; /*!< context for the entropy function */
#if defined(MBEDTLS_THREADING_C)
/* Invariant: the mutex is initialized if and only if
* md_ctx->md_info != NULL. This means that the mutex is initialized
* during the initial seeding in mbedtls_hmac_drbg_seed() or
* mbedtls_hmac_drbg_seed_buf() and freed in mbedtls_ctr_drbg_free().
*
* Note that this invariant may change without notice. Do not rely on it
* and do not access the mutex directly in application code.
*/
mbedtls_threading_mutex_t mutex;
#endif
} mbedtls_hmac_drbg_context;

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@ -284,6 +284,7 @@ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 )
return( ret );
/* The mutex is initialized iff the md context is set up. */
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &ctx->mutex );
#endif
@ -455,6 +456,7 @@ void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx )
return;
#if defined(MBEDTLS_THREADING_C)
/* The mutex is initialized iff the md context is set up. */
if( ctx->md_ctx.md_info != NULL )
mbedtls_mutex_free( &ctx->mutex );
#endif