On Tue, Jan 12, 2021 at 10:56 AM Cong Wang <xiyou.wangc...@gmail.com> wrote:
>
> From: Cong Wang <cong.w...@bytedance.com>
>
> fl_set_enc_opt() simply checks if there are still bytes left to parse,
> but this is not sufficent as syzbot seems to be able to generate
> malformatted netlink messages. nla_ok() is more strict so should be
> used to validate the next nlattr here.
>
> And nla_validate_nested_deprecated() has less strict check too, it is
> probably too late to switch to the strict version, but we can just
> call nla_ok() too after it.
>
> Reported-and-tested-by: syzbot+2624e3778b18fc497...@syzkaller.appspotmail.com
> Fixes: 0a6e77784f49 ("net/sched: allow flower to match tunnel options")
> Fixes: 79b1011cb33d ("net: sched: allow flower to match erspan options")
> Cc: Pieter Jansen van Vuuren <pieter.jansenvanvuu...@netronome.com>
> Cc: Jamal Hadi Salim <j...@mojatatu.com>
> Cc: Xin Long <lucien....@gmail.com>
> Cc: Jiri Pirko <j...@resnulli.us>
> Signed-off-by: Cong Wang <cong.w...@bytedance.com>
> ---
> net/sched/cls_flower.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index 1319986693fc..e265c443536e 100644
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -1272,6 +1272,8 @@ static int fl_set_enc_opt(struct nlattr **tb, struct
> fl_flow_key *key,
>
> nla_opt_msk = nla_data(tb[TCA_FLOWER_KEY_ENC_OPTS_MASK]);
> msk_depth = nla_len(tb[TCA_FLOWER_KEY_ENC_OPTS_MASK]);
> + if (!nla_ok(nla_opt_msk, msk_depth))
> + return -EINVAL;
> }
I think it's better to also add NL_SET_ERR_MSG(extack, xxxx);
for this error return, like all the other places in this function.
>
> nla_for_each_attr(nla_opt_key, nla_enc_key,
> @@ -1308,7 +1310,7 @@ static int fl_set_enc_opt(struct nlattr **tb, struct
> fl_flow_key *key,
> return -EINVAL;
> }
>
> - if (msk_depth)
> + if (nla_ok(nla_opt_msk, msk_depth))
> nla_opt_msk = nla_next(nla_opt_msk,
> &msk_depth);
> break;
> case TCA_FLOWER_KEY_ENC_OPTS_VXLAN:
> @@ -1341,7 +1343,7 @@ static int fl_set_enc_opt(struct nlattr **tb, struct
> fl_flow_key *key,
> return -EINVAL;
> }
>
> - if (msk_depth)
> + if (nla_ok(nla_opt_msk, msk_depth))
> nla_opt_msk = nla_next(nla_opt_msk,
> &msk_depth);
> break;
> case TCA_FLOWER_KEY_ENC_OPTS_ERSPAN:
> @@ -1374,7 +1376,7 @@ static int fl_set_enc_opt(struct nlattr **tb, struct
> fl_flow_key *key,
> return -EINVAL;
> }
>
> - if (msk_depth)
> + if (nla_ok(nla_opt_msk, msk_depth))
> nla_opt_msk = nla_next(nla_opt_msk,
> &msk_depth);
> break;
> default:
> --
> 2.25.1
>
