crypto/x509/x509_vfy.c:878: error: NULL_DEREFERENCE
  pointer `xs` last assigned on line 870 could be null and is dereferenced at line 878, column 8.
Showing all 32 steps of the trace


crypto/x509/x509_vfy.c:841:1: start of procedure internal_verify()
839.   	}
840.   
841. > static int internal_verify(X509_STORE_CTX *ctx)
842.   	{
843.   	int ok=0,n;

crypto/x509/x509_vfy.c:843:2: 
841.   static int internal_verify(X509_STORE_CTX *ctx)
842.   	{
843. > 	int ok=0,n;
844.   	X509 *xs,*xi;
845.   	EVP_PKEY *pkey=NULL;

crypto/x509/x509_vfy.c:845:2: 
843.   	int ok=0,n;
844.   	X509 *xs,*xi;
845. > 	EVP_PKEY *pkey=NULL;
846.   	int (*cb)();
847.   

crypto/x509/x509_vfy.c:848:2: 
846.   	int (*cb)();
847.   
848. > 	cb=ctx->verify_cb;
849.   
850.   	n=sk_X509_num(ctx->chain);

crypto/x509/x509_vfy.c:850:2: 
848.   	cb=ctx->verify_cb;
849.   
850. > 	n=sk_X509_num(ctx->chain);
851.   	ctx->error_depth=n-1;
852.   	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:851:2: 
849.   
850.   	n=sk_X509_num(ctx->chain);
851. > 	ctx->error_depth=n-1;
852.   	n--;
853.   	xi=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:852:2: 
850.   	n=sk_X509_num(ctx->chain);
851.   	ctx->error_depth=n-1;
852. > 	n--;
853.   	xi=sk_X509_value(ctx->chain,n);
854.   

crypto/x509/x509_vfy.c:853:2: 
851.   	ctx->error_depth=n-1;
852.   	n--;
853. > 	xi=sk_X509_value(ctx->chain,n);
854.   
855.   	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:855:6: Taking false branch
853.   	xi=sk_X509_value(ctx->chain,n);
854.   
855.   	if (ctx->check_issued(ctx, xi, xi))
            ^
856.   		xs=xi;
857.   	else

crypto/x509/x509_vfy.c:859:7: Taking false branch
857.   	else
858.   		{
859.   		if (n <= 0)
             ^
860.   			{
861.   			ctx->error=X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE;

crypto/x509/x509_vfy.c:868:4: 
866.   		else
867.   			{
868. > 			n--;
869.   			ctx->error_depth=n;
870.   			xs=sk_X509_value(ctx->chain,n);

crypto/x509/x509_vfy.c:869:4: 
867.   			{
868.   			n--;
869. > 			ctx->error_depth=n;
870.   			xs=sk_X509_value(ctx->chain,n);
871.   			}

crypto/x509/x509_vfy.c:870:4: 
868.   			n--;
869.   			ctx->error_depth=n;
870. > 			xs=sk_X509_value(ctx->chain,n);
871.   			}
872.   		}

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:875:9: Loop condition is true. Entering loop body
873.   
874.   /*	ctx->error=0;  not needed */
875.   	while (n >= 0)
               ^
876.   		{
877.   		ctx->error_depth=n;

crypto/x509/x509_vfy.c:877:3: 
875.   	while (n >= 0)
876.   		{
877. > 		ctx->error_depth=n;
878.   		if (!xs->valid)
879.   			{

crypto/x509/x509_vfy.c:878:8: Taking false branch
876.   		{
877.   		ctx->error_depth=n;
878.   		if (!xs->valid)
              ^
879.   			{
880.   			if ((pkey=X509_get_pubkey(xi)) == NULL)
