crypto/x509/x509_vfy.c:977: error: NULL_DEREFERENCE
  pointer `xs` last assigned on line 969 could be null and is dereferenced at line 977, column 8.
Showing all 32 steps of the trace


crypto/x509/x509_vfy.c:940:1: start of procedure internal_verify()
938.   	}
939.   
940. > static int internal_verify(X509_STORE_CTX *ctx)
941.   	{
942.   	int ok=0,n;

crypto/x509/x509_vfy.c:942:2: 
940.   static int internal_verify(X509_STORE_CTX *ctx)
941.   	{
942. > 	int ok=0,n;
943.   	X509 *xs,*xi;
944.   	EVP_PKEY *pkey=NULL;

crypto/x509/x509_vfy.c:944:2: 
942.   	int ok=0,n;
943.   	X509 *xs,*xi;
944. > 	EVP_PKEY *pkey=NULL;
945.   	int (*cb)(int xok,X509_STORE_CTX *xctx);
946.   

crypto/x509/x509_vfy.c:947:2: 
945.   	int (*cb)(int xok,X509_STORE_CTX *xctx);
946.   
947. > 	cb=ctx->verify_cb;
948.   
949.   	n=sk_X509_num(ctx->chain);

crypto/x509/x509_vfy.c:949:2: 
947.   	cb=ctx->verify_cb;
948.   
949. > 	n=sk_X509_num(ctx->chain);
950.   	ctx->error_depth=n-1;
951.   	n--;

crypto/stack/stack.c:301:1: start of procedure sk_num()
  299.   	}
  300.   
  301. > int sk_num(const STACK *st)
  302.   {
  303.   	if(st == NULL) return -1;

crypto/stack/stack.c:303:5: Taking false branch
  301.   int sk_num(const STACK *st)
  302.   {
  303.   	if(st == NULL) return -1;
             ^
  304.   	return st->num;
  305.   }

crypto/stack/stack.c:304:2: 
  302.   {
  303.   	if(st == NULL) return -1;
  304. > 	return st->num;
  305.   }
  306.   

crypto/stack/stack.c:305:1: return from a call to sk_num
  303.   	if(st == NULL) return -1;
  304.   	return st->num;
  305. > }
  306.   
  307.   char *sk_value(const STACK *st, int i)

crypto/x509/x509_vfy.c:950:2: 
948.   
949.   	n=sk_X509_num(ctx->chain);
950. > 	ctx->error_depth=n-1;
951.   	n--;
952.   	xi=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:951:2: 
949.   	n=sk_X509_num(ctx->chain);
950.   	ctx->error_depth=n-1;
951. > 	n--;
952.   	xi=sk_X509_value(ctx->chain,n);
953.   

crypto/x509/x509_vfy.c:952:2: 
950.   	ctx->error_depth=n-1;
951.   	n--;
952. > 	xi=sk_X509_value(ctx->chain,n);
953.   
954.   	if (ctx->check_issued(ctx, xi, xi))

crypto/stack/stack.c:307:1: start of procedure sk_value()
  305.   }
  306.   
  307. > char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;

crypto/stack/stack.c:309:6: Taking false branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
              ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:309:13: Taking false branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
                     ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:309:24: Taking false branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
                                ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:310:2: 
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
  310. > 	return st->data[i];
  311.   }
  312.   

crypto/stack/stack.c:311:1: return from a call to sk_value
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
  310.   	return st->data[i];
  311. > }
  312.   
  313.   char *sk_set(STACK *st, int i, char *value)

crypto/x509/x509_vfy.c:954:6: Taking false branch
952.   	xi=sk_X509_value(ctx->chain,n);
953.   
954.   	if (ctx->check_issued(ctx, xi, xi))
            ^
955.   		xs=xi;
956.   	else

crypto/x509/x509_vfy.c:958:7: Taking false branch
956.   	else
957.   		{
958.   		if (n <= 0)
             ^
959.   			{
960.   			ctx->error=X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE;

crypto/x509/x509_vfy.c:967:4: 
965.   		else
966.   			{
967. > 			n--;
968.   			ctx->error_depth=n;
969.   			xs=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:968:4: 
966.   			{
967.   			n--;
968. > 			ctx->error_depth=n;
969.   			xs=sk_X509_value(ctx->chain,n);
970.   			}

crypto/x509/x509_vfy.c:969:4: 
967.   			n--;
968.   			ctx->error_depth=n;
969. > 			xs=sk_X509_value(ctx->chain,n);
970.   			}
971.   		}

crypto/stack/stack.c:307:1: start of procedure sk_value()
  305.   }
  306.   
  307. > char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;

crypto/stack/stack.c:309:6: Taking false branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
              ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:309:13: Taking false branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
                     ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:309:24: Taking true branch
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
                                ^
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:309:39: 
  307.   char *sk_value(const STACK *st, int i)
  308.   {
  309. > 	if(!st || (i < 0) || (i >= st->num)) return NULL;
  310.   	return st->data[i];
  311.   }

crypto/stack/stack.c:311:1: return from a call to sk_value
  309.   	if(!st || (i < 0) || (i >= st->num)) return NULL;
  310.   	return st->data[i];
  311. > }
  312.   
  313.   char *sk_set(STACK *st, int i, char *value)

crypto/x509/x509_vfy.c:974:9: Loop condition is true. Entering loop body
972.   
973.   /*	ctx->error=0;  not needed */
974.   	while (n >= 0)
               ^
975.   		{
976.   		ctx->error_depth=n;

crypto/x509/x509_vfy.c:976:3: 
974.   	while (n >= 0)
975.   		{
976. > 		ctx->error_depth=n;
977.   		if (!xs->valid)
978.   			{

crypto/x509/x509_vfy.c:977:8: Taking false branch
975.   		{
976.   		ctx->error_depth=n;
977.   		if (!xs->valid)
              ^
978.   			{
979.   			if ((pkey=X509_get_pubkey(xi)) == NULL)
