hello Cong, thank you for reviewing this.
On Wed, 2018-03-14 at 11:41 -0700, Cong Wang wrote:
> On Tue, Mar 13, 2018 at 7:13 PM, Davide Caratti <dcara...@redhat.com> wrote:
>
> Looks like we just need to replace the tcf_idr_cleanup() with
> tcf_idr_release()? Which is also simpler.
I just tried it on act_simple, and I can confirm: 'index' does not leak
anymore if alloc_defdata() fails to kzalloc(), and then tcf_idr_release()
is called in place of of tcf_idr_cleanup().
> Looks like all other callers of tcf_idr_cleanup() need to be replaced too,
> but I don't audit all of them...
no problem, I can try to do that, it's not going to be a big series
anyway.
while at it, I will also fix other spots where the same bug can be
reproduced, even if tcf_idr_cleanup() is not there: for example, when
tcf_vlan_init() fails allocating struct tcf_vlan_params *p,
ASSERT_RTNL();
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p) {
if (ovr)
tcf_idr_release(*a, bind);
return -ENOMEM;
}
the followinng behavior can be observed:
# tc actions flush action vlan
# tc actions add action vlan pop index 5
RTNETLINK answers: Cannot allocate memory
We have an error talking to the kernel
# tc actions add action vlan pop index 5
RTNETLINK answers: No space left on device
We have an error talking to the kernel
# tc actions add action vlan pop index 5
RTNETLINK answers: No space left on device
We have an error talking to the kernel
Probably testing the value of 'ovr' here is wrong, or maybe it's
not enough: I will also verify what happens using 'replace'
keyword instead of 'add'.
>
> [...]
>
> > if (!exists) {
> > + defdata = nla_strdup(tb[TCA_DEF_DATA], GFP_KERNEL);
> > + if (unlikely(!defdata))
> > + return -ENOMEM;
> > +
> > ret = tcf_idr_create(tn, parm->index, est, a,
> > &act_simp_ops, bind, false);
> > if (ret)
> > return ret;
>
> You leak memory here on failure, BTW.
Ouch, you are right. I was wrongly convinced that act_simp_ops.cleanup()
was called also in case of failure of tcf_idr_create(), but it's not true.
Indeed, a call to act_simp_ops.cleanup() happens if we call
tcf_idr_release() after tcf_idr_create() returned 0.
regards,
--
davide
