Thu, Oct 10, 2019 at 11:13:47AM CEST, [email protected] wrote: >On Thu, Oct 10, 2019 at 10:39:58AM +0200, Jiri Pirko wrote: >> Wed, Oct 09, 2019 at 06:44:32PM CEST, [email protected] wrote: >> >Commit c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing >> >to a separate function") moved attribute buffer allocation and attribute >> >parsing from genl_family_rcv_msg_doit() into a separate function >> >genl_family_rcv_msg_attrs_parse() which, unlike the previous code, calls >> >__nlmsg_parse() even if family->maxattr is 0 (i.e. the family does its own >> >parsing). The parser error is ignored and does not propagate out of >> >genl_family_rcv_msg_attrs_parse() but an error message ("Unknown attribute >> >type") is set in extack and if further processing generates no error or >> >warning, it stays there and is interpreted as a warning by userspace. >> > >> >Dumpit requests are not affected as genl_family_rcv_msg_dumpit() bypasses >> >the call of genl_family_rcv_msg_doit() if family->maxattr is zero. Do the >> >same also in genl_family_rcv_msg_doit(). >> >> This is the original code before the changes: >> >> if (ops->doit == NULL) >> return -EOPNOTSUPP; >> >> if (family->maxattr && family->parallel_ops) { >> attrbuf = kmalloc_array(family->maxattr + 1, >> sizeof(struct nlattr *), >> GFP_KERNEL); >> if (attrbuf == NULL) >> return -ENOMEM; >> } else >> attrbuf = family->attrbuf; >> >> if (attrbuf) { >> enum netlink_validation validate = NL_VALIDATE_STRICT; >> >> if (ops->validate & GENL_DONT_VALIDATE_STRICT) >> validate = NL_VALIDATE_LIBERAL; >> >> err = __nlmsg_parse(nlh, hdrlen, attrbuf, family->maxattr, >> family->policy, validate, extack); >> if (err < 0) >> goto out; >> } >> >> Looks like the __nlmsg_parse() is called no matter if maxattr if 0 or >> not. It is only considered for allocation of attrbuf. This is in-sync >> with the current code. > >If family->maxattr is 0, genl_register_family() sets family->attrbuf to >NULL so that attrbuf is also NULL and the whole "if (attrbuf) { ... }" >block is not executed.
Ah, I missed that. Thanks! > >Michal
