Commit c96adff9 authored by Cong Wang's avatar Cong Wang Committed by Jakub Kicinski
Browse files

cls_flower: call nla_ok() before nla_next() 



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: default avatar <syzbot+2624e3778b18fc497c92@syzkaller.appspotmail.com>
Fixes: 0a6e7778 ("net/sched: allow flower to match tunnel options")
Fixes: 79b1011c ("net: sched: allow flower to match erspan options")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Xin Long <lucien.xin@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarCong Wang <cong.wang@bytedance.com>
Link: https://lore.kernel.org/r/20210115185024.72298-1-xiyou.wangcong@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent b7ba6cfa

net/sched/cls_flower.c

+13 −9
Original line number Diff line number Diff line
@@ -1272,6 +1272,10 @@ 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)) {

			NL_SET_ERR_MSG(extack, "Invalid nested attribute for masks");

			return -EINVAL;

		}

	}



	nla_for_each_attr(nla_opt_key, nla_enc_key,
@@ -1307,9 +1311,6 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key, 
				NL_SET_ERR_MSG(extack, "Key and mask miss aligned");

				return -EINVAL;

			}



			if (msk_depth)

				nla_opt_msk = nla_next(nla_opt_msk, &msk_depth);

			break;

		case TCA_FLOWER_KEY_ENC_OPTS_VXLAN:

			if (key->enc_opts.dst_opt_type) {
@@ -1340,9 +1341,6 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key, 
				NL_SET_ERR_MSG(extack, "Key and mask miss aligned");

				return -EINVAL;

			}



			if (msk_depth)

				nla_opt_msk = nla_next(nla_opt_msk, &msk_depth);

			break;

		case TCA_FLOWER_KEY_ENC_OPTS_ERSPAN:

			if (key->enc_opts.dst_opt_type) {
@@ -1373,14 +1371,20 @@ static int fl_set_enc_opt(struct nlattr **tb, struct fl_flow_key *key, 
				NL_SET_ERR_MSG(extack, "Key and mask miss aligned");

				return -EINVAL;

			}



			if (msk_depth)

				nla_opt_msk = nla_next(nla_opt_msk, &msk_depth);

			break;

		default:

			NL_SET_ERR_MSG(extack, "Unknown tunnel option type");

			return -EINVAL;

		}



		if (!msk_depth)

			continue;



		if (!nla_ok(nla_opt_msk, msk_depth)) {

			NL_SET_ERR_MSG(extack, "A mask attribute is invalid");

			return -EINVAL;

		}

		nla_opt_msk = nla_next(nla_opt_msk, &msk_depth);

	}



	return 0;