[PATCH net v4] Fix u32's systematic failure to free IDR entries for hnodes.
DORMANTno replies
From: Alexandre Ferrieux <hidden>
Date: 2024-11-07 22:53:14
Subsystem:
kernel selftest framework, networking [general], tc subsystem, the rest · Maintainers:
Shuah Khan, Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
To generate hnode handles (in gen_new_htid()), u32 uses IDR and
encodes the returned small integer into a structured 32-bit
word. Unfortunately, at disposal time, the needed decoding
is not done. As a result, idr_remove() fails, and the IDR
fills up. Since its size is 2048, the following script ends up
with "Filter already exists":
tc filter add dev myve $FILTER1
tc filter add dev myve $FILTER2
for i in {1..2048}
do
echo $i
tc filter del dev myve $FILTER2
tc filter add dev myve $FILTER2
done
This patch adds the missing decoding logic for handles that
deserve it, along with a corresponding tdc test.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Alexandre Ferrieux <redacted>
---
v4: add tdc test
v3: prepend title with subsystem ident
v2: use u32 type in handle encoder/decoder
net/sched/cls_u32.c | 18 ++++++++++----
.../tc-testing/tc-tests/filters/u32.json | 24 +++++++++++++++++++
2 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 9412d88a99bc..6da94b809926 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c@@ -41,6 +41,16 @@ #include <linux/idr.h> #include <net/tc_wrapper.h> +static inline u32 handle2id(u32 h) +{ + return ((h & 0x80000000) ? ((h >> 20) & 0x7FF) : h); +} + +static inline u32 id2handle(u32 id) +{ + return (id | 0x800U) << 20; +} + struct tc_u_knode { struct tc_u_knode __rcu *next; u32 handle;
@@ -310,7 +320,7 @@ static u32 gen_new_htid(struct tc_u_common *tp_c, struct tc_u_hnode *ptr) int id = idr_alloc_cyclic(&tp_c->handle_idr, ptr, 1, 0x7FF, GFP_KERNEL); if (id < 0) return 0; - return (id | 0x800U) << 20; + return id2handle(id); } static struct hlist_head *tc_u_common_hash;
@@ -360,7 +370,7 @@ static int u32_init(struct tcf_proto *tp) return -ENOBUFS; refcount_set(&root_ht->refcnt, 1); - root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : 0x80000000; + root_ht->handle = tp_c ? gen_new_htid(tp_c, root_ht) : id2handle(0); root_ht->prio = tp->prio; root_ht->is_root = true; idr_init(&root_ht->handle_idr);
@@ -612,7 +622,7 @@ static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht, if (phn == ht) { u32_clear_hw_hnode(tp, ht, extack); idr_destroy(&ht->handle_idr); - idr_remove(&tp_c->handle_idr, ht->handle); + idr_remove(&tp_c->handle_idr, handle2id(ht->handle)); RCU_INIT_POINTER(*hn, ht->next); kfree_rcu(ht, rcu); return 0;
@@ -989,7 +999,7 @@ static int u32_change(struct net *net, struct sk_buff *in_skb, err = u32_replace_hw_hnode(tp, ht, userflags, extack); if (err) { - idr_remove(&tp_c->handle_idr, handle); + idr_remove(&tp_c->handle_idr, handle2id(handle)); kfree(ht); return err; }
diff --git a/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json b/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
index 24bd0c2a3014..2095baa19c6a 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/filters/u32.json@@ -329,5 +329,29 @@ "teardown": [ "$TC qdisc del dev $DEV1 parent root drr" ] + }, + { + "id": "1234", + "name": "Exercise IDR leaks by creating/deleting a filter many (2048) times", + "category": [ + "filter", + "u32" + ], + "plugins": { + "requires": "nsPlugin" + }, + "setup": [ + "$TC qdisc add dev $DEV1 parent root handle 10: drr", + "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 2 u32 match ip src 0.0.0.2/32 action drop", + "$TC filter add dev $DEV1 parent 10:0 protocol ip prio 3 u32 match ip src 0.0.0.3/32 action drop" + ], + "cmdUnderTest": "bash -c 'for i in {1..2048} ;do $TC filter delete dev $DEV1 pref 3;$TC filter add dev $DEV1 parent 10:0 protocol ip prio 3 u32 match ip src 0.0.0.3/32 action drop || exit 1;i=`expr $i + 1`;done'", + "expExitCode": "0", + "verifyCmd": "$TC filter show dev $DEV1", + "matchPattern": "protocol ip pref 3 u32", + "matchCount": "3", + "teardown": [ + "$TC qdisc del dev $DEV1 parent root drr" + ] } ]
--
2.30.2