crypto/x509/x509_vfy.c:941: error: NULL_DEREFERENCE
  pointer `xs` last assigned on line 933 could be null and is dereferenced at line 941, column 8.
Showing all 32 steps of the trace


crypto/x509/x509_vfy.c:904:1: start of procedure internal_verify()
902.   	}
903.   
904. > static int internal_verify(X509_STORE_CTX *ctx)
905.   	{
906.   	int ok=0,n;

crypto/x509/x509_vfy.c:906:2: 
904.   static int internal_verify(X509_STORE_CTX *ctx)
905.   	{
906. > 	int ok=0,n;
907.   	X509 *xs,*xi;
908.   	EVP_PKEY *pkey=NULL;

crypto/x509/x509_vfy.c:908:2: 
906.   	int ok=0,n;
907.   	X509 *xs,*xi;
908. > 	EVP_PKEY *pkey=NULL;
909.   	int (*cb)();
910.   

crypto/x509/x509_vfy.c:911:2: 
909.   	int (*cb)();
910.   
911. > 	cb=ctx->verify_cb;
912.   
913.   	n=sk_X509_num(ctx->chain);

crypto/x509/x509_vfy.c:913:2: 
911.   	cb=ctx->verify_cb;
912.   
913. > 	n=sk_X509_num(ctx->chain);
914.   	ctx->error_depth=n-1;
915.   	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:914:2: 
912.   
913.   	n=sk_X509_num(ctx->chain);
914. > 	ctx->error_depth=n-1;
915.   	n--;
916.   	xi=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:915:2: 
913.   	n=sk_X509_num(ctx->chain);
914.   	ctx->error_depth=n-1;
915. > 	n--;
916.   	xi=sk_X509_value(ctx->chain,n);
917.   

crypto/x509/x509_vfy.c:916:2: 
914.   	ctx->error_depth=n-1;
915.   	n--;
916. > 	xi=sk_X509_value(ctx->chain,n);
917.   
918.   	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:918:6: Taking false branch
916.   	xi=sk_X509_value(ctx->chain,n);
917.   
918.   	if (ctx->check_issued(ctx, xi, xi))
            ^
919.   		xs=xi;
920.   	else

crypto/x509/x509_vfy.c:922:7: Taking false branch
920.   	else
921.   		{
922.   		if (n <= 0)
             ^
923.   			{
924.   			ctx->error=X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE;

crypto/x509/x509_vfy.c:931:4: 
929.   		else
930.   			{
931. > 			n--;
932.   			ctx->error_depth=n;
933.   			xs=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:932:4: 
930.   			{
931.   			n--;
932. > 			ctx->error_depth=n;
933.   			xs=sk_X509_value(ctx->chain,n);
934.   			}

crypto/x509/x509_vfy.c:933:4: 
931.   			n--;
932.   			ctx->error_depth=n;
933. > 			xs=sk_X509_value(ctx->chain,n);
934.   			}
935.   		}

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:938:9: Loop condition is true. Entering loop body
936.   
937.   /*	ctx->error=0;  not needed */
938.   	while (n >= 0)
               ^
939.   		{
940.   		ctx->error_depth=n;

crypto/x509/x509_vfy.c:940:3: 
938.   	while (n >= 0)
939.   		{
940. > 		ctx->error_depth=n;
941.   		if (!xs->valid)
942.   			{

crypto/x509/x509_vfy.c:941:8: Taking false branch
939.   		{
940.   		ctx->error_depth=n;
941.   		if (!xs->valid)
              ^
942.   			{
943.   			if ((pkey=X509_get_pubkey(xi)) == NULL)
