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: Jamal Hadi Salim <j...@mojatatu.com> Cc: Xin Long <lucien....@gmail.com> Cc: Jiri Pirko <j...@resnulli.us> Cc: Jakub Kicinski <k...@kernel.org> Signed-off-by: Cong Wang <cong.w...@bytedance.com> --- net/sched/cls_flower.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index 1319986693fc..84f932532db7 100644 --- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -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; -- 2.25.1