Quoting Dmitry V. Levin (2016-06-23 11:36:25)
> On Thu, Jun 23, 2016 at 10:49:53AM +0000, Fabien Siron wrote:
> > Quoting Dmitry V. Levin (2016-06-22 17:40:39)
> > > On Wed, Jun 22, 2016 at 01:27:06PM +0000, Fabien Siron wrote:
[...]
> > > > + if (NLMSG_ALIGN(nlmsghdr->nlmsg_len) == 0 ||
> > > > + NLMSG_ALIGN(nlmsghdr->nlmsg_len) > *len)
> > > > + return 0;
> > >
> > > This is not going to happen with current implementation of nlmsg_fetch,
> > > but if nlmsg_fetch changes and if this condition is true, then
> > > *len remains unchanged and the subsequent nlmsg_fetch prints NULL.
> >
> > A way to fix that is to put *len to 0 in this test. But the problem is that
> > nothing will be printed if sizeof(struct nlmsghdr) < *len <
> > nlmsghdr->nlmsg_len.
>
> It's up to decode_netlink_msg to decide how to print such messages.
>
> decode_netlink has to be consistent. Every successfully fetched struct
> nlmsghdr should be printed. When decode_netlink leaves some bytes of the
> message undecoded, it has to print an indication.
It already prints a string, what kind of indication do you want to add?
So do you agree with this test for next_nlmsghdr:
if (NLMSG_ALIGN(nlmsghdr->nlmsg_len) == 0 ||
NLMSG_ALIGN(nlmsghdr->nlmsg_len) > *len) {
*len = nlmsghdr->nlmsg_len;
return 0;
}
Now, the subsequent nlmsg_fetch does not print NULL.
Regards,
--
Fabien Siron
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