net/smc: fix invalid return code in smcd_new_buf_create()

smc_ism_register_dmb() returns error codes set by the ISM driver which
are not guaranteed to be negative or in the errno range. Such values
would not be handled by ERR_PTR() and finally the return code will be
used as a memory address.
Fix that by using a valid negative errno value with ERR_PTR().

Fixes: 72b7f6c487 ("net/smc: unique reason code for exceeded max dmb count")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/smc/smc_core.c

@@ -1616,7 +1616,8 @@ static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
 		rc = smc_ism_register_dmb(lgr, bufsize, buf_desc);
 		if (rc) {
 			kfree(buf_desc);
-			return (rc == -ENOMEM) ? ERR_PTR(-EAGAIN) : ERR_PTR(rc);
+			return (rc == -ENOMEM) ? ERR_PTR(-EAGAIN) :
+						 ERR_PTR(-EIO);
 		}
 		buf_desc->pages = virt_to_page(buf_desc->cpu_addr);
 		/* CDC header stored in buf. So, pretend it was smaller */