Re: [PATCH net-next v3] genetlink: do not parse attributes for families with zero maxattr

[Jakub Kicinski]

On Fri, 11 Oct 2019 09:40:09 +0200, 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_attrs_parse() if family->maxattr is zero.
> Move this logic inside genl_family_rcv_msg_attrs_parse() so that we don't
> have to handle it in each caller.
> 
> v3: put the check inside genl_family_rcv_msg_attrs_parse()
> v2: adjust also argument of genl_family_rcv_msg_attrs_free()
> 
> Fixes: c10e6cf85e7d ("net: genetlink: push attrbuf allocation and parsing to a separate function")
> Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>

Acked-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>