On Thu, Oct 10, 2019 at 10:21:02AM -0700, Jakub Kicinski wrote: > On Thu, 10 Oct 2019 12:34:02 +0200 (CEST), Michal Kubecek 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(). > > > > Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing > > to a separate function") > > Signed-off-by: Michal Kubecek <mkube...@suse.cz> > > --- > > net/netlink/genetlink.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c > > index ecc2bd3e73e4..1f14e55ad3ad 100644 > > --- a/net/netlink/genetlink.c > > +++ b/net/netlink/genetlink.c > > @@ -639,21 +639,23 @@ static int genl_family_rcv_msg_doit(const struct > > genl_family *family, > > const struct genl_ops *ops, > > int hdrlen, struct net *net) > > { > > - struct nlattr **attrbuf; > > + struct nlattr **attrbuf = NULL; > > struct genl_info info; > > int err; > > > > if (!ops->doit) > > return -EOPNOTSUPP; > > > > + if (!family->maxattr) > > + goto no_attrs; > > attrbuf = genl_family_rcv_msg_attrs_parse(family, nlh, extack, > > ops, hdrlen, > > GENL_DONT_VALIDATE_STRICT, > > - family->maxattr && > > family->parallel_ops); > > if (IS_ERR(attrbuf)) > > return PTR_ERR(attrbuf); > > > > +no_attrs: > > The use of a goto statement as a replacement for an if is making me > uncomfortable.
I used instead of a simple if because (1) it's what the dumpit code does and (2) the function call arguments are already quite pressed to the 80-character barrier. > Looks like both callers of genl_family_rcv_msg_attrs_parse() jump > around it if !family->maxattr and then check the result with IS_ERR(). > > Would it not make more sense to have genl_family_rcv_msg_attrs_parse() > return NULL if !family->maxattr? This sounds like a good solution. I'll check again in the morning and send v3. Michal