From: Cong Wang cong.wang@bytedance.com
commit c96adff95619178e2118925578343ad54857c80c upstream.
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+2624e3778b18fc497c92@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 jhs@mojatatu.com Cc: Xin Long lucien.xin@gmail.com Cc: Jiri Pirko jiri@resnulli.us Signed-off-by: Cong Wang cong.wang@bytedance.com Link: https://lore.kernel.org/r/20210115185024.72298-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/sched/cls_flower.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
--- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -1272,6 +1272,10 @@ static int fl_set_enc_opt(struct nlattr
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 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 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 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;