Don't bother to free NULL subcontexts
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 3fddc4e..73389bb 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -172,6 +172,7 @@
#define ECDSA_BUDGET( ops ) \
MBEDTLS_MPI_CHK( mbedtls_ecp_check_budget( grp, &rs_ctx->ecp, ops ) );
+/* Call this when entering a function that needs its own sub-context */
#define ECDSA_RS_ENTER( SUB ) do { \
/* reset ops count for this call if top-level */ \
if( rs_ctx != NULL && rs_ctx->ecp.depth++ == 0 ) \
@@ -189,9 +190,11 @@
} \
} while( 0 )
+/* Call this when leaving a function that needs its own sub-context */
#define ECDSA_RS_LEAVE( SUB ) do { \
/* clear our sub-context when not in progress (done or error) */ \
- if( rs_ctx != NULL && ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) \
+ if( rs_ctx != NULL && rs_ctx->SUB != NULL && \
+ ret != MBEDTLS_ERR_ECP_IN_PROGRESS ) \
{ \
ecdsa_restart_## SUB ##_free( rs_ctx->SUB ); \
mbedtls_free( rs_ctx->SUB ); \
