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Miller" , Sasha Levin Subject: [PATCH 6.1 0581/1887] net/sched: flower: Fix chain template offload Date: Wed, 28 Oct 2026 17:44:37 +0100 Message-ID: <20261028170512.640518902@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ido Schimmel [ Upstream commit 32f2a0afa95fae0d1ceec2ff06e0e816939964b8 ] When a qdisc is deleted from a net device the stack instructs the underlying driver to remove its flow offload callback from the associated filter block using the 'FLOW_BLOCK_UNBIND' command. The stack then continues to replay the removal of the filters in the block for this driver by iterating over the chains in the block and invoking the 'reoffload' operation of the classifier being used. In turn, the classifier in its 'reoffload' operation prepares and emits a 'FLOW_CLS_DESTROY' command for each filter. However, the stack does not do the same for chain templates and the underlying driver never receives a 'FLOW_CLS_TMPLT_DESTROY' command when a qdisc is deleted. This results in a memory leak [1] which can be reproduced using [2]. Fix by introducing a 'tmplt_reoffload' operation and have the stack invoke it with the appropriate arguments as part of the replay. Implement the operation in the sole classifier that supports chain templates (flower) by emitting the 'FLOW_CLS_TMPLT_{CREATE,DESTROY}' command based on whether a flow offload callback is being bound to a filter block or being unbound from one. As far as I can tell, the issue happens since cited commit which reordered tcf_block_offload_unbind() before tcf_block_flush_all_chains() in __tcf_block_put(). The order cannot be reversed as the filter block is expected to be freed after flushing all the chains. [1] unreferenced object 0xffff888107e28800 (size 2048): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): b1 a6 7c 11 81 88 ff ff e0 5b b3 10 81 88 ff ff ..|......[...... 01 00 00 00 00 00 00 00 e0 aa b0 84 ff ff ff ff ................ backtrace: [] __kmem_cache_alloc_node+0x1e8/0x320 [] __kmalloc+0x4e/0x90 [] mlxsw_sp_acl_ruleset_get+0x34d/0x7a0 [] mlxsw_sp_flower_tmplt_create+0x145/0x180 [] mlxsw_sp_flow_block_cb+0x1ea/0x280 [] tc_setup_cb_call+0x183/0x340 [] fl_tmplt_create+0x3da/0x4c0 [] tc_ctl_chain+0xa15/0x1170 [] rtnetlink_rcv_msg+0x3cc/0xed0 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x540/0x820 [] netlink_sendmsg+0x8d8/0xda0 [] ____sys_sendmsg+0x30f/0xa80 [] ___sys_sendmsg+0x13a/0x1e0 [] __sys_sendmsg+0x11c/0x1f0 [] do_syscall_64+0x40/0xe0 unreferenced object 0xffff88816d2c0400 (size 1024): comm "tc", pid 1079, jiffies 4294958525 (age 3074.287s) hex dump (first 32 bytes): 40 00 00 00 00 00 00 00 57 f6 38 be 00 00 00 00 @.......W.8..... 10 04 2c 6d 81 88 ff ff 10 04 2c 6d 81 88 ff ff ..,m......,m.... backtrace: [] __kmem_cache_alloc_node+0x1e8/0x320 [] __kmalloc_node+0x51/0x90 [] kvmalloc_node+0xa6/0x1f0 [] bucket_table_alloc.isra.0+0x83/0x460 [] rhashtable_init+0x43b/0x7c0 [] mlxsw_sp_acl_ruleset_get+0x428/0x7a0 [] mlxsw_sp_flower_tmplt_create+0x145/0x180 [] mlxsw_sp_flow_block_cb+0x1ea/0x280 [] tc_setup_cb_call+0x183/0x340 [] fl_tmplt_create+0x3da/0x4c0 [] tc_ctl_chain+0xa15/0x1170 [] rtnetlink_rcv_msg+0x3cc/0xed0 [] netlink_rcv_skb+0x170/0x440 [] netlink_unicast+0x540/0x820 [] netlink_sendmsg+0x8d8/0xda0 [] ____sys_sendmsg+0x30f/0xa80 [2] # tc qdisc add dev swp1 clsact # tc chain add dev swp1 ingress proto ip chain 1 flower dst_ip 0.0.0.0/32 # tc qdisc del dev swp1 clsact # devlink dev reload pci/0000:06:00.0 Fixes: bbf73830cd48 ("net: sched: traverse chains in block with tcf_get_next_chain()") Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/sch_generic.h | 4 ++++ net/sched/cls_api.c | 9 ++++++++- net/sched/cls_flower.c | 23 +++++++++++++++++++++++ 3 files changed, 35 insertions(+), 1 deletion(-) diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h index 7ec1f5aa6adaf..b694d27f41714 100644 --- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -378,6 +378,10 @@ struct tcf_proto_ops { struct nlattr **tca, struct netlink_ext_ack *extack); void (*tmplt_destroy)(void *tmplt_priv); + void (*tmplt_reoffload)(struct tcf_chain *chain, + bool add, + flow_setup_cb_t *cb, + void *cb_priv); /* rtnetlink specific */ int (*dump)(struct net*, struct tcf_proto*, void *, diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index dbaf6e72aa2da..9ee545b0364ad 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -1431,6 +1431,9 @@ tcf_block_playback_offloads(struct tcf_block *block, flow_setup_cb_t *cb, chain_prev = chain, chain = __tcf_get_next_chain(block, chain), tcf_chain_put(chain_prev)) { + if (chain->tmplt_ops && add) + chain->tmplt_ops->tmplt_reoffload(chain, true, cb, + cb_priv); for (tp = __tcf_get_next_proto(chain, NULL); tp; tp_prev = tp, tp = __tcf_get_next_proto(chain, tp), @@ -1446,6 +1449,9 @@ tcf_block_playback_offloads(struct tcf_block *block, flow_setup_cb_t *cb, goto err_playback_remove; } } + if (chain->tmplt_ops && !add) + chain->tmplt_ops->tmplt_reoffload(chain, false, cb, + cb_priv); } return 0; @@ -2861,7 +2867,8 @@ static int tc_chain_tmplt_add(struct tcf_chain *chain, struct net *net, ops = tcf_proto_lookup_ops(name, true, extack); if (IS_ERR(ops)) return PTR_ERR(ops); - if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump) { + if (!ops->tmplt_create || !ops->tmplt_destroy || !ops->tmplt_dump || + !ops->tmplt_reoffload) { NL_SET_ERR_MSG(extack, "Chain templates are not supported with specified classifier"); module_put(ops->owner); return -EOPNOTSUPP; diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index a40a9e84c75f4..42234a0101e78 100644 --- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -2596,6 +2596,28 @@ static void fl_tmplt_destroy(void *tmplt_priv) kfree(tmplt); } +static void fl_tmplt_reoffload(struct tcf_chain *chain, bool add, + flow_setup_cb_t *cb, void *cb_priv) +{ + struct fl_flow_tmplt *tmplt = chain->tmplt_priv; + struct flow_cls_offload cls_flower = {}; + + cls_flower.rule = flow_rule_alloc(0); + if (!cls_flower.rule) + return; + + cls_flower.common.chain_index = chain->index; + cls_flower.command = add ? FLOW_CLS_TMPLT_CREATE : + FLOW_CLS_TMPLT_DESTROY; + cls_flower.cookie = (unsigned long) tmplt; + cls_flower.rule->match.dissector = &tmplt->dissector; + cls_flower.rule->match.mask = &tmplt->mask; + cls_flower.rule->match.key = &tmplt->dummy_key; + + cb(TC_SETUP_CLSFLOWER, &cls_flower, cb_priv); + kfree(cls_flower.rule); +} + static int fl_dump_key_val(struct sk_buff *skb, void *val, int val_type, void *mask, int mask_type, int len) @@ -3452,6 +3474,7 @@ static struct tcf_proto_ops cls_fl_ops __read_mostly = { .bind_class = fl_bind_class, .tmplt_create = fl_tmplt_create, .tmplt_destroy = fl_tmplt_destroy, + .tmplt_reoffload = fl_tmplt_reoffload, .tmplt_dump = fl_tmplt_dump, .owner = THIS_MODULE, .flags = TCF_PROTO_OPS_DOIT_UNLOCKED, -- 2.53.0