test/drbgtest.c:535: error: NULL_DEREFERENCE
  pointer `ctx` last assigned on line 533 could be null and is dereferenced at line 535, column 25.
Showing all 13 steps of the trace


test/drbgtest.c:531:1: start of procedure unhook_drbg()
529.   
530.   /* Installs the hook for the get_entropy() callback of the given drbg */
531. > static void unhook_drbg(RAND_DRBG *drbg)
532.   {
533.       HOOK_CTX *ctx = get_hook_ctx(drbg);

test/drbgtest.c:533:5: 
531.   static void unhook_drbg(RAND_DRBG *drbg)
532.   {
533. >     HOOK_CTX *ctx = get_hook_ctx(drbg);
534.   
535.       drbg->get_entropy = ctx->get_entropy;

test/drbgtest.c:497:1: start of procedure get_hook_ctx()
  495.   static HOOK_CTX master_ctx, public_ctx, private_ctx;
  496.   
  497. > static HOOK_CTX *get_hook_ctx(RAND_DRBG *drbg)
  498.   {
  499.       return (HOOK_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);

test/drbgtest.c:499:5: 
  497.   static HOOK_CTX *get_hook_ctx(RAND_DRBG *drbg)
  498.   {
  499. >     return (HOOK_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);
  500.   }
  501.   

crypto/rand/drbg_lib.c:617:1: start of procedure RAND_DRBG_get_ex_data()
    615.   }
    616.   
    617. > void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
    618.   {
    619.       return CRYPTO_get_ex_data(&drbg->ex_data, idx);

crypto/rand/drbg_lib.c:619:5: 
    617.   void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
    618.   {
    619. >     return CRYPTO_get_ex_data(&drbg->ex_data, idx);
    620.   }
    621.   

crypto/ex_data.c:393:1: start of procedure CRYPTO_get_ex_data()
      391.    * particular index in the class used by this variable
      392.    */
      393. > void *CRYPTO_get_ex_data(const CRYPTO_EX_DATA *ad, int idx)
      394.   {
      395.       if (ad->sk == NULL || idx >= sk_void_num(ad->sk))

crypto/ex_data.c:395:9: Taking true branch
      393.   void *CRYPTO_get_ex_data(const CRYPTO_EX_DATA *ad, int idx)
      394.   {
      395.       if (ad->sk == NULL || idx >= sk_void_num(ad->sk))
                     ^
      396.           return NULL;
      397.       return sk_void_value(ad->sk, idx);

crypto/ex_data.c:396:9: 
      394.   {
      395.       if (ad->sk == NULL || idx >= sk_void_num(ad->sk))
      396. >         return NULL;
      397.       return sk_void_value(ad->sk, idx);
      398.   }

crypto/ex_data.c:398:1: return from a call to CRYPTO_get_ex_data
      396.           return NULL;
      397.       return sk_void_value(ad->sk, idx);
      398. > }

crypto/rand/drbg_lib.c:620:1: return from a call to RAND_DRBG_get_ex_data
    618.   {
    619.       return CRYPTO_get_ex_data(&drbg->ex_data, idx);
    620. > }
    621.   
    622.   

test/drbgtest.c:500:1: return from a call to get_hook_ctx
  498.   {
  499.       return (HOOK_CTX *)RAND_DRBG_get_ex_data(drbg, app_data_index);
  500. > }
  501.   
  502.   /* Intercepts and counts calls to the get_entropy() callback */

test/drbgtest.c:535:5: 
533.       HOOK_CTX *ctx = get_hook_ctx(drbg);
534.   
535. >     drbg->get_entropy = ctx->get_entropy;
536.       CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
537.   }
