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authorCong Wang <xiyou.wangcong@gmail.com>2020-09-03 19:10:11 -0700
committerJakub Kicinski <kuba@kernel.org>2020-09-04 22:08:59 -0700
commitcc8e58f8325cdf14b9516b61c384cdfd02a4f408 (patch)
tree2160b26ff40843ab785308ceacab79263d1026fd /net
parentc2b947879ca320ac5505c6c29a731ff17da5e805 (diff)
downloadlinux-cc8e58f8325cdf14b9516b61c384cdfd02a4f408.tar.bz2
act_ife: load meta modules before tcf_idr_check_alloc()
The following deadlock scenario is triggered by syzbot: Thread A: Thread B: tcf_idr_check_alloc() ... populate_metalist() rtnl_unlock() rtnl_lock() ... request_module() tcf_idr_check_alloc() rtnl_lock() At this point, thread A is waiting for thread B to release RTNL lock, while thread B is waiting for thread A to commit the IDR change with tcf_idr_insert() later. Break this deadlock situation by preloading ife modules earlier, before tcf_idr_check_alloc(), this is fine because we only need to load modules we need potentially. Reported-and-tested-by: syzbot+80e32b5d1f9923f8ace6@syzkaller.appspotmail.com Fixes: 0190c1d452a9 ("net: sched: atomically check-allocate action") Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Vlad Buslov <vladbu@mellanox.com> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/sched/act_ife.c44
1 files changed, 34 insertions, 10 deletions
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index c1fcd85719d6..5c568757643b 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -436,6 +436,25 @@ static void tcf_ife_cleanup(struct tc_action *a)
kfree_rcu(p, rcu);
}
+static int load_metalist(struct nlattr **tb, bool rtnl_held)
+{
+ int i;
+
+ for (i = 1; i < max_metacnt; i++) {
+ if (tb[i]) {
+ void *val = nla_data(tb[i]);
+ int len = nla_len(tb[i]);
+ int rc;
+
+ rc = load_metaops_and_vet(i, val, len, rtnl_held);
+ if (rc != 0)
+ return rc;
+ }
+ }
+
+ return 0;
+}
+
static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb,
bool exists, bool rtnl_held)
{
@@ -449,10 +468,6 @@ static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb,
val = nla_data(tb[i]);
len = nla_len(tb[i]);
- rc = load_metaops_and_vet(i, val, len, rtnl_held);
- if (rc != 0)
- return rc;
-
rc = add_metainfo(ife, i, val, len, exists);
if (rc)
return rc;
@@ -509,6 +524,21 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
if (!p)
return -ENOMEM;
+ if (tb[TCA_IFE_METALST]) {
+ err = nla_parse_nested_deprecated(tb2, IFE_META_MAX,
+ tb[TCA_IFE_METALST], NULL,
+ NULL);
+ if (err) {
+ kfree(p);
+ return err;
+ }
+ err = load_metalist(tb2, rtnl_held);
+ if (err) {
+ kfree(p);
+ return err;
+ }
+ }
+
index = parm->index;
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (err < 0) {
@@ -570,15 +600,9 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
}
if (tb[TCA_IFE_METALST]) {
- err = nla_parse_nested_deprecated(tb2, IFE_META_MAX,
- tb[TCA_IFE_METALST], NULL,
- NULL);
- if (err)
- goto metadata_parse_err;
err = populate_metalist(ife, tb2, exists, rtnl_held);
if (err)
goto metadata_parse_err;
-
} else {
/* if no passed metadata allow list or passed allow-all
* then here we process by adding as many supported metadatum