From 6855e8213e06efcaf7c02a15e12b1ae64b9a7149 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Tue, 30 Mar 2021 04:23:23 +0530 Subject: net: sched: bump refcount for new action in ACT replace mode Currently, action creation using ACT API in replace mode is buggy. When invoking for non-existent action index 42, tc action replace action bpf obj foo.o sec index 42 kernel creates the action, fills up the netlink response, and then just deletes the action after notifying userspace. tc action show action bpf doesn't list the action. This happens due to the following sequence when ovr = 1 (replace mode) is enabled: tcf_idr_check_alloc is used to atomically check and either obtain reference for existing action at index, or reserve the index slot using a dummy entry (ERR_PTR(-EBUSY)). This is necessary as pointers to these actions will be held after dropping the idrinfo lock, so bumping the reference count is necessary as we need to insert the actions, and notify userspace by dumping their attributes. Finally, we drop the reference we took using the tcf_action_put_many call in tcf_action_add. However, for the case where a new action is created due to free index, its refcount remains one. This when paired with the put_many call leads to the kernel setting up the action, notifying userspace of its creation, and then tearing it down. For existing actions, the refcount is still held so they remain unaffected. Fortunately due to rtnl_lock serialization requirement, such an action with refcount == 1 will not be concurrently deleted by anything else, at best CLS API can move its refcount up and down by binding to it after it has been published from tcf_idr_insert_many. Since refcount is atleast one until put_many call, CLS API cannot delete it. Also __tcf_action_put release path already ensures deterministic outcome (either new action will be created or existing action will be reused in case CLS API tries to bind to action concurrently) due to idr lock serialization. We fix this by making refcount of newly created actions as 2 in ACT API replace mode. A relaxed store will suffice as visibility is ensured only after the tcf_idr_insert_many call. Note that in case of creation or overwriting using CLS API only (i.e. bind = 1), overwriting existing action object is not allowed, and any such request is silently ignored (without error). The refcount bump that occurs in tcf_idr_check_alloc call there for existing action will pair with tcf_exts_destroy call made from the owner module for the same action. In case of action creation, there is no existing action, so no tcf_exts_destroy callback happens. This means no code changes for CLS API. Fixes: cae422f379f3 ("net: sched: use reference counting action init") Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: David S. Miller --- net/sched/act_api.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/sched') diff --git a/net/sched/act_api.c b/net/sched/act_api.c index b919826939e0..43cceb924976 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -1042,6 +1042,9 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, if (err != ACT_P_CREATED) module_put(a_o->owner); + if (!bind && ovr && err == ACT_P_CREATED) + refcount_set(&a->tcfa_refcnt, 2); + return a; err_out: -- cgit v1.2.3 From ae81feb7338c89cee4e6aa0424bdab2ce2b52da2 Mon Sep 17 00:00:00 2001 From: Yunjian Wang Date: Tue, 30 Mar 2021 22:27:48 +0800 Subject: sch_htb: fix null pointer dereference on a null new_q sch_htb: fix null pointer dereference on a null new_q Currently if new_q is null, the null new_q pointer will be dereference when 'q->offload' is true. Fix this by adding a braces around htb_parent_to_leaf_offload() to avoid it. Addresses-Coverity: ("Dereference after null check") Fixes: d03b195b5aa0 ("sch_htb: Hierarchical QoS hardware offload") Signed-off-by: Yunjian Wang Signed-off-by: David S. Miller --- net/sched/sch_htb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'net/sched') diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 62e12cb41a3e..081c11d5717c 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -1675,9 +1675,10 @@ static int htb_delete(struct Qdisc *sch, unsigned long arg, cl->parent->common.classid, NULL); if (q->offload) { - if (new_q) + if (new_q) { htb_set_lockdep_class_child(new_q); - htb_parent_to_leaf_offload(sch, dev_queue, new_q); + htb_parent_to_leaf_offload(sch, dev_queue, new_q); + } } } -- cgit v1.2.3 From 990b03b05b2fba79de2a1ee9dc359fc552d95ba6 Mon Sep 17 00:00:00 2001 From: Yunjian Wang Date: Thu, 1 Apr 2021 12:52:48 +0800 Subject: net: cls_api: Fix uninitialised struct field bo->unlocked_driver_cb The 'unlocked_driver_cb' struct field in 'bo' is not being initialized in tcf_block_offload_init(). The uninitialized 'unlocked_driver_cb' will be used when calling unlocked_driver_cb(). So initialize 'bo' to zero to avoid the issue. Addresses-Coverity: ("Uninitialized scalar variable") Fixes: 0fdcf78d5973 ("net: use flow_indr_dev_setup_offload()") Signed-off-by: Yunjian Wang Signed-off-by: David S. Miller --- net/sched/cls_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sched') diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 13341e7fb077..9332ec6863e8 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -646,7 +646,7 @@ static void tc_block_indr_cleanup(struct flow_block_cb *block_cb) struct net_device *dev = block_cb->indr.dev; struct Qdisc *sch = block_cb->indr.sch; struct netlink_ext_ack extack = {}; - struct flow_block_offload bo; + struct flow_block_offload bo = {}; tcf_block_offload_init(&bo, dev, sch, FLOW_BLOCK_UNBIND, block_cb->indr.binder_type, -- cgit v1.2.3 From 4ba86128ba077fbb7d86516ae24ed642e6c3adef Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Wed, 7 Apr 2021 18:36:02 +0300 Subject: Revert "net: sched: bump refcount for new action in ACT replace mode" This reverts commit 6855e8213e06efcaf7c02a15e12b1ae64b9a7149. Following commit in series fixes the issue without introducing regression in error rollback of tcf_action_destroy(). Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller --- net/sched/act_api.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'net/sched') diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 43cceb924976..b919826939e0 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -1042,9 +1042,6 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, if (err != ACT_P_CREATED) module_put(a_o->owner); - if (!bind && ovr && err == ACT_P_CREATED) - refcount_set(&a->tcfa_refcnt, 2); - return a; err_out: -- cgit v1.2.3 From 87c750e8c38bce706eb32e4d8f1e3402f2cebbd4 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Wed, 7 Apr 2021 18:36:03 +0300 Subject: net: sched: fix action overwrite reference counting Action init code increments reference counter when it changes an action. This is the desired behavior for cls API which needs to obtain action reference for every classifier that points to action. However, act API just needs to change the action and releases the reference before returning. This sequence breaks when the requested action doesn't exist, which causes act API init code to create new action with specified index, but action is still released before returning and is deleted (unless it was referenced concurrently by cls API). Reproduction: $ sudo tc actions ls action gact $ sudo tc actions change action gact drop index 1 $ sudo tc actions ls action gact Extend tcf_action_init() to accept 'init_res' array and initialize it with action->ops->init() result. In tcf_action_add() remove pointers to created actions from actions array before passing it to tcf_action_put_many(). Fixes: cae422f379f3 ("net: sched: use reference counting action init") Reported-by: Kumar Kartikeya Dwivedi Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller --- include/net/act_api.h | 5 +++-- net/sched/act_api.c | 22 +++++++++++++++------- net/sched/cls_api.c | 9 +++++---- 3 files changed, 23 insertions(+), 13 deletions(-) (limited to 'net/sched') diff --git a/include/net/act_api.h b/include/net/act_api.h index 2bf3092ae7ec..312f0f6554a0 100644 --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -185,7 +185,7 @@ int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions, int nr_actions, struct tcf_result *res); int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action *actions[], size_t *attr_size, + struct tc_action *actions[], int init_res[], size_t *attr_size, bool rtnl_held, struct netlink_ext_ack *extack); struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, bool rtnl_held, @@ -193,7 +193,8 @@ struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action_ops *ops, bool rtnl_held, + struct tc_action_ops *a_o, int *init_res, + bool rtnl_held, struct netlink_ext_ack *extack); int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[], int bind, int ref, bool terse); diff --git a/net/sched/act_api.c b/net/sched/act_api.c index b919826939e0..50854cfbfcdb 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -992,7 +992,8 @@ struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action_ops *a_o, bool rtnl_held, + struct tc_action_ops *a_o, int *init_res, + bool rtnl_held, struct netlink_ext_ack *extack) { struct nla_bitfield32 flags = { 0, 0 }; @@ -1028,6 +1029,7 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, } if (err < 0) goto err_out; + *init_res = err; if (!name && tb[TCA_ACT_COOKIE]) tcf_set_action_cookie(&a->act_cookie, cookie); @@ -1056,7 +1058,7 @@ err_out: int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action *actions[], size_t *attr_size, + struct tc_action *actions[], int init_res[], size_t *attr_size, bool rtnl_held, struct netlink_ext_ack *extack) { struct tc_action_ops *ops[TCA_ACT_MAX_PRIO] = {}; @@ -1084,7 +1086,8 @@ int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { act = tcf_action_init_1(net, tp, tb[i], est, name, ovr, bind, - ops[i - 1], rtnl_held, extack); + ops[i - 1], &init_res[i - 1], rtnl_held, + extack); if (IS_ERR(act)) { err = PTR_ERR(act); goto err; @@ -1497,12 +1500,13 @@ static int tcf_action_add(struct net *net, struct nlattr *nla, struct netlink_ext_ack *extack) { size_t attr_size = 0; - int loop, ret; + int loop, ret, i; struct tc_action *actions[TCA_ACT_MAX_PRIO] = {}; + int init_res[TCA_ACT_MAX_PRIO] = {}; for (loop = 0; loop < 10; loop++) { ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, - actions, &attr_size, true, extack); + actions, init_res, &attr_size, true, extack); if (ret != -EAGAIN) break; } @@ -1510,8 +1514,12 @@ static int tcf_action_add(struct net *net, struct nlattr *nla, if (ret < 0) return ret; ret = tcf_add_notify(net, n, actions, portid, attr_size, extack); - if (ovr) - tcf_action_put_many(actions); + + /* only put existing actions */ + for (i = 0; i < TCA_ACT_MAX_PRIO; i++) + if (init_res[i] == ACT_P_CREATED) + actions[i] = NULL; + tcf_action_put_many(actions); return ret; } diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 9332ec6863e8..9ecb91ebf094 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -3040,6 +3040,7 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, { #ifdef CONFIG_NET_CLS_ACT { + int init_res[TCA_ACT_MAX_PRIO] = {}; struct tc_action *act; size_t attr_size = 0; @@ -3051,8 +3052,8 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, return PTR_ERR(a_o); act = tcf_action_init_1(net, tp, tb[exts->police], rate_tlv, "police", ovr, - TCA_ACT_BIND, a_o, rtnl_held, - extack); + TCA_ACT_BIND, a_o, init_res, + rtnl_held, extack); if (IS_ERR(act)) { module_put(a_o->owner); return PTR_ERR(act); @@ -3067,8 +3068,8 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, err = tcf_action_init(net, tp, tb[exts->action], rate_tlv, NULL, ovr, TCA_ACT_BIND, - exts->actions, &attr_size, - rtnl_held, extack); + exts->actions, init_res, + &attr_size, rtnl_held, extack); if (err < 0) return err; exts->nr_actions = err; -- cgit v1.2.3 From b3650bf76a32380d4d80a3e21b5583e7303f216c Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Wed, 7 Apr 2021 18:36:04 +0300 Subject: net: sched: fix err handler in tcf_action_init() With recent changes that separated action module load from action initialization tcf_action_init() function error handling code was modified to manually release the loaded modules if loading/initialization of any further action in same batch failed. For the case when all modules successfully loaded and some of the actions were initialized before one of them failed in init handler. In this case for all previous actions the module will be released twice by the error handler: First time by the loop that manually calls module_put() for all ops, and second time by the action destroy code that puts the module after destroying the action. Reproduction: $ sudo tc actions add action simple sdata \"2\" index 2 $ sudo tc actions add action simple sdata \"1\" index 1 \ action simple sdata \"2\" index 2 RTNETLINK answers: File exists We have an error talking to the kernel $ sudo tc actions ls action simple total acts 1 action order 0: Simple <"2"> index 2 ref 1 bind 0 $ sudo tc actions flush action simple $ sudo tc actions ls action simple $ sudo tc actions add action simple sdata \"2\" index 2 Error: Failed to load TC action module. We have an error talking to the kernel $ lsmod | grep simple act_simple 20480 -1 Fix the issue by modifying module reference counting handling in action initialization code: - Get module reference in tcf_idr_create() and put it in tcf_idr_release() instead of taking over the reference held by the caller. - Modify users of tcf_action_init_1() to always release the module reference which they obtain before calling init function instead of assuming that created action takes over the reference. - Finally, modify tcf_action_init_1() to not release the module reference when overwriting existing action as this is no longer necessary since both upper and lower layers obtain and manage their own module references independently. Fixes: d349f9976868 ("net_sched: fix RTNL deadlock again caused by request_module()") Suggested-by: Cong Wang Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller --- include/net/act_api.h | 7 +------ net/sched/act_api.c | 26 ++++++++++++++++---------- net/sched/cls_api.c | 5 ++--- 3 files changed, 19 insertions(+), 19 deletions(-) (limited to 'net/sched') diff --git a/include/net/act_api.h b/include/net/act_api.h index 312f0f6554a0..086b291e9530 100644 --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -170,12 +170,7 @@ void tcf_idr_insert_many(struct tc_action *actions[]); void tcf_idr_cleanup(struct tc_action_net *tn, u32 index); int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index, struct tc_action **a, int bind); -int __tcf_idr_release(struct tc_action *a, bool bind, bool strict); - -static inline int tcf_idr_release(struct tc_action *a, bool bind) -{ - return __tcf_idr_release(a, bind, false); -} +int tcf_idr_release(struct tc_action *a, bool bind); int tcf_register_action(struct tc_action_ops *a, struct pernet_operations *ops); int tcf_unregister_action(struct tc_action_ops *a, diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 50854cfbfcdb..f6d5755d669e 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -158,7 +158,7 @@ static int __tcf_action_put(struct tc_action *p, bool bind) return 0; } -int __tcf_idr_release(struct tc_action *p, bool bind, bool strict) +static int __tcf_idr_release(struct tc_action *p, bool bind, bool strict) { int ret = 0; @@ -184,7 +184,18 @@ int __tcf_idr_release(struct tc_action *p, bool bind, bool strict) return ret; } -EXPORT_SYMBOL(__tcf_idr_release); + +int tcf_idr_release(struct tc_action *a, bool bind) +{ + const struct tc_action_ops *ops = a->ops; + int ret; + + ret = __tcf_idr_release(a, bind, false); + if (ret == ACT_P_DELETED) + module_put(ops->owner); + return ret; +} +EXPORT_SYMBOL(tcf_idr_release); static size_t tcf_action_shared_attrs_size(const struct tc_action *act) { @@ -493,6 +504,7 @@ int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est, } p->idrinfo = idrinfo; + __module_get(ops->owner); p->ops = ops; *a = p; return 0; @@ -1037,13 +1049,6 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, if (!name) a->hw_stats = hw_stats; - /* module count goes up only when brand new policy is created - * if it exists and is only bound to in a_o->init() then - * ACT_P_CREATED is not returned (a zero is). - */ - if (err != ACT_P_CREATED) - module_put(a_o->owner); - return a; err_out: @@ -1103,7 +1108,8 @@ int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, tcf_idr_insert_many(actions); *attr_size = tcf_action_full_attrs_size(sz); - return i - 1; + err = i - 1; + goto err_mod; err: tcf_action_destroy(actions, bind); diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index 9ecb91ebf094..340d5af86e87 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -3054,10 +3054,9 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, rate_tlv, "police", ovr, TCA_ACT_BIND, a_o, init_res, rtnl_held, extack); - if (IS_ERR(act)) { - module_put(a_o->owner); + module_put(a_o->owner); + if (IS_ERR(act)) return PTR_ERR(act); - } act->type = exts->type = TCA_OLD_COMPAT; exts->actions[0] = act; -- cgit v1.2.3 From 1ffbc7ea91606e4abd10eb60de5367f1c86daf5e Mon Sep 17 00:00:00 2001 From: Pavel Tikhomirov Date: Thu, 8 Apr 2021 18:14:31 +0300 Subject: net: sched: sch_teql: fix null-pointer dereference Reproduce: modprobe sch_teql tc qdisc add dev teql0 root teql0 This leads to (for instance in Centos 7 VM) OOPS: [ 532.366633] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a8 [ 532.366733] IP: [] teql_destroy+0x18/0x100 [sch_teql] [ 532.366825] PGD 80000001376d5067 PUD 137e37067 PMD 0 [ 532.366906] Oops: 0000 [#1] SMP [ 532.366987] Modules linked in: sch_teql ... [ 532.367945] CPU: 1 PID: 3026 Comm: tc Kdump: loaded Tainted: G ------------ T 3.10.0-1062.7.1.el7.x86_64 #1 [ 532.368041] Hardware name: Virtuozzo KVM, BIOS 1.11.0-2.vz7.2 04/01/2014 [ 532.368125] task: ffff8b7d37d31070 ti: ffff8b7c9fdbc000 task.ti: ffff8b7c9fdbc000 [ 532.368224] RIP: 0010:[] [] teql_destroy+0x18/0x100 [sch_teql] [ 532.368320] RSP: 0018:ffff8b7c9fdbf8e0 EFLAGS: 00010286 [ 532.368394] RAX: ffffffffc0612490 RBX: ffff8b7cb1565e00 RCX: ffff8b7d35ba2000 [ 532.368476] RDX: ffff8b7d35ba2000 RSI: 0000000000000000 RDI: ffff8b7cb1565e00 [ 532.368557] RBP: ffff8b7c9fdbf8f8 R08: ffff8b7d3fd1f140 R09: ffff8b7d3b001600 [ 532.368638] R10: ffff8b7d3b001600 R11: ffffffff84c7d65b R12: 00000000ffffffd8 [ 532.368719] R13: 0000000000008000 R14: ffff8b7d35ba2000 R15: ffff8b7c9fdbf9a8 [ 532.368800] FS: 00007f6a4e872740(0000) GS:ffff8b7d3fd00000(0000) knlGS:0000000000000000 [ 532.368885] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 532.368961] CR2: 00000000000000a8 CR3: 00000001396ee000 CR4: 00000000000206e0 [ 532.369046] Call Trace: [ 532.369159] [] qdisc_create+0x36e/0x450 [ 532.369268] [] ? ns_capable+0x29/0x50 [ 532.369366] [] ? nla_parse+0x32/0x120 [ 532.369442] [] tc_modify_qdisc+0x13c/0x610 [ 532.371508] [] rtnetlink_rcv_msg+0xa7/0x260 [ 532.372668] [] ? sock_has_perm+0x75/0x90 [ 532.373790] [] ? rtnl_newlink+0x890/0x890 [ 532.374914] [] netlink_rcv_skb+0xab/0xc0 [ 532.376055] [] rtnetlink_rcv+0x28/0x30 [ 532.377204] [] netlink_unicast+0x170/0x210 [ 532.378333] [] netlink_sendmsg+0x308/0x420 [ 532.379465] [] sock_sendmsg+0xb6/0xf0 [ 532.380710] [] ? __xfs_filemap_fault+0x8e/0x1d0 [xfs] [ 532.381868] [] ? xfs_filemap_fault+0x2c/0x30 [xfs] [ 532.383037] [] ? __do_fault.isra.61+0x8a/0x100 [ 532.384144] [] ___sys_sendmsg+0x3e9/0x400 [ 532.385268] [] ? handle_mm_fault+0x39d/0x9b0 [ 532.386387] [] ? __do_page_fault+0x238/0x500 [ 532.387472] [] __sys_sendmsg+0x51/0x90 [ 532.388560] [] SyS_sendmsg+0x12/0x20 [ 532.389636] [] system_call_fastpath+0x25/0x2a [ 532.390704] [] ? system_call_after_swapgs+0xae/0x146 [ 532.391753] Code: 00 00 00 00 00 00 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 e5 41 55 41 54 53 48 8b b7 48 01 00 00 48 89 fb <48> 8b 8e a8 00 00 00 48 85 c9 74 43 48 89 ca eb 0f 0f 1f 80 00 [ 532.394036] RIP [] teql_destroy+0x18/0x100 [sch_teql] [ 532.395127] RSP [ 532.396179] CR2: 00000000000000a8 Null pointer dereference happens on master->slaves dereference in teql_destroy() as master is null-pointer. When qdisc_create() calls teql_qdisc_init() it imediately fails after check "if (m->dev == dev)" because both devices are teql0, and it does not set qdisc_priv(sch)->m leaving it zero on error path, then qdisc_create() imediately calls teql_destroy() which does not expect zero master pointer and we get OOPS. Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation") Signed-off-by: Pavel Tikhomirov Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_teql.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/sched') diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c index 2f1f0a378408..6af6b95bdb67 100644 --- a/net/sched/sch_teql.c +++ b/net/sched/sch_teql.c @@ -134,6 +134,9 @@ teql_destroy(struct Qdisc *sch) struct teql_sched_data *dat = qdisc_priv(sch); struct teql_master *master = dat->m; + if (!master) + return; + prev = master->slaves; if (prev) { do { -- cgit v1.2.3