[PATCH net 0/9] net/sched: init failure fixes

[PATCH net 0/9] net/sched: init failure fixes

[Nikolay Aleksandrov]

Hi all,
I went over all qdiscs' init, destroy and reset callbacks and found the
issues fixed in each patch. Mostly they are null pointer dereferences due
to uninitialized timer (qdisc watchdog) or double frees due to ->destroy
cleaning up a second time. There's more information in each patch.
I've tested these by either sending wrong attributes from user-spaces, no
attributes or by simulating memory alloc failure where applicable. Also
tried all of the qdiscs as a default qdisc.

Most of these bugs were present before commit 87b60cfacf9f, I've tried to
include proper fixes tags in each patch.

I haven't included individual patch acks in the set, I'd appreciate it if
you take another look and resend them.

Thanks,
 Nik

Nikolay Aleksandrov (9):
  sch_htb: fix crash on init failure
  sch_multiq: fix double free on init failure
  sch_hhf: fix null pointer dereference on init failure
  sch_hfsc: fix null pointer deref and double free on init failure
  sch_cbq: fix null pointer dereferences on init failure
  sch_fq_codel: avoid double free on init failure
  sch_netem: avoid null pointer deref on init failure
  sch_sfq: fix null pointer dereference on init failure
  sch_tbf: fix two null pointer dereferences on init failure

 net/sched/sch_cbq.c      | 10 +++++++---
 net/sched/sch_fq_codel.c |  4 +---
 net/sched/sch_hfsc.c     | 10 +++-------
 net/sched/sch_hhf.c      |  3 +++
 net/sched/sch_htb.c      |  5 +++--
 net/sched/sch_multiq.c   |  7 +------
 net/sched/sch_netem.c    |  4 ++--
 net/sched/sch_sfq.c      |  6 +++---
 net/sched/sch_tbf.c      |  5 +++--
 9 files changed, 26 insertions(+), 28 deletions(-)

-- 
2.1.4

[PATCH net 1/9] sch_htb: fix crash on init failure

[Nikolay Aleksandrov]

The commit below added a call to the ->destroy() callback for all qdiscs
which failed in their ->init(), but some were not prepared for such
change and can't handle partially initialized qdisc. HTB is one of them
and if any error occurs before the qdisc watchdog timer and qdisc work are
initialized then we can hit either a null ptr deref (timer->base) when
canceling in ->destroy or lockdep error info about trying to register
a non-static key and a stack dump. So to fix these two move the watchdog
timer and workqueue init before anything that can err out.
To reproduce userspace needs to send broken htb qdisc create request,
tested with a modified tc (q_htb.c).

Trace log:
[ 2710.897602] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 2710.897977] IP: hrtimer_active+0x17/0x8a
[ 2710.898174] PGD 58fab067
[ 2710.898175] P4D 58fab067
[ 2710.898353] PUD 586c0067
[ 2710.898531] PMD 0
[ 2710.898710]
[ 2710.899045] Oops: 0000 [#1] SMP
[ 2710.899232] Modules linked in:
[ 2710.899419] CPU: 1 PID: 950 Comm: tc Not tainted 4.13.0-rc6+ #54
[ 2710.899646] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 2710.900035] task: ffff880059ed2700 task.stack: ffff88005ad4c000
[ 2710.900262] RIP: 0010:hrtimer_active+0x17/0x8a
[ 2710.900467] RSP: 0018:ffff88005ad4f960 EFLAGS: 00010246
[ 2710.900684] RAX: 0000000000000000 RBX: ffff88003701e298 RCX: 0000000000000000
[ 2710.900933] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88003701e298
[ 2710.901177] RBP: ffff88005ad4f980 R08: 0000000000000001 R09: 0000000000000001
[ 2710.901419] R10: ffff88005ad4f800 R11: 0000000000000400 R12: 0000000000000000
[ 2710.901663] R13: ffff88003701e298 R14: ffffffff822a4540 R15: ffff88005ad4fac0
[ 2710.901907] FS:  00007f2f5e90f740(0000) GS:ffff88005d880000(0000) knlGS:0000000000000000
[ 2710.902277] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2710.902500] CR2: 0000000000000000 CR3: 0000000058ca3000 CR4: 00000000000406e0
[ 2710.902744] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 2710.902977] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 2710.903180] Call Trace:
[ 2710.903332]  hrtimer_try_to_cancel+0x1a/0x93
[ 2710.903504]  hrtimer_cancel+0x15/0x20
[ 2710.903667]  qdisc_watchdog_cancel+0x12/0x14
[ 2710.903866]  htb_destroy+0x2e/0xf7
[ 2710.904097]  qdisc_create+0x377/0x3fd
[ 2710.904330]  tc_modify_qdisc+0x4d2/0x4fd
[ 2710.904511]  rtnetlink_rcv_msg+0x188/0x197
[ 2710.904682]  ? rcu_read_unlock+0x3e/0x5f
[ 2710.904849]  ? rtnl_newlink+0x729/0x729
[ 2710.905017]  netlink_rcv_skb+0x6c/0xce
[ 2710.905183]  rtnetlink_rcv+0x23/0x2a
[ 2710.905345]  netlink_unicast+0x103/0x181
[ 2710.905511]  netlink_sendmsg+0x326/0x337
[ 2710.905679]  sock_sendmsg_nosec+0x14/0x3f
[ 2710.905847]  sock_sendmsg+0x29/0x2e
[ 2710.906010]  ___sys_sendmsg+0x209/0x28b
[ 2710.906176]  ? do_raw_spin_unlock+0xcd/0xf8
[ 2710.906346]  ? _raw_spin_unlock+0x27/0x31
[ 2710.906514]  ? __handle_mm_fault+0x651/0xdb1
[ 2710.906685]  ? check_chain_key+0xb0/0xfd
[ 2710.906855]  __sys_sendmsg+0x45/0x63
[ 2710.907018]  ? __sys_sendmsg+0x45/0x63
[ 2710.907185]  SyS_sendmsg+0x19/0x1b
[ 2710.907344]  entry_SYSCALL_64_fastpath+0x23/0xc2

Note that probably this bug goes further back because the default qdisc
handling always calls ->destroy on init failure too.

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Fixes: 0fbbeb1ba43b ("[PKT_SCHED]: Fix missing qdisc_destroy() in qdisc_create_dflt()")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_htb.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 5d65ec5207e9..5bf5177b2bd3 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1017,6 +1017,9 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt)
 	int err;
 	int i;
 
+	qdisc_watchdog_init(&q->watchdog, sch);
+	INIT_WORK(&q->work, htb_work_func);
+
 	if (!opt)
 		return -EINVAL;
 
@@ -1041,8 +1044,6 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt)
 	for (i = 0; i < TC_HTB_NUMPRIO; i++)
 		INIT_LIST_HEAD(q->drops + i);
 
-	qdisc_watchdog_init(&q->watchdog, sch);
-	INIT_WORK(&q->work, htb_work_func);
 	qdisc_skb_head_init(&q->direct_queue);
 
 	if (tb[TCA_HTB_DIRECT_QLEN])
-- 
2.1.4

[PATCH net 2/9] sch_multiq: fix double free on init failure

[Nikolay Aleksandrov]

The below commit added a call to ->destroy() on init failure, but multiq
still frees ->queues on error in init, but ->queues is also freed by
->destroy() thus we get double free and corrupted memory.

Very easy to reproduce (eth0 not multiqueue):
$ tc qdisc add dev eth0 root multiq
RTNETLINK answers: Operation not supported
$ ip l add dumdum type dummy
(crash)

Trace log:
[ 3929.467747] general protection fault: 0000 [#1] SMP
[ 3929.468083] Modules linked in:
[ 3929.468302] CPU: 3 PID: 967 Comm: ip Not tainted 4.13.0-rc6+ #56
[ 3929.468625] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 3929.469124] task: ffff88003716a700 task.stack: ffff88005872c000
[ 3929.469449] RIP: 0010:__kmalloc_track_caller+0x117/0x1be
[ 3929.469746] RSP: 0018:ffff88005872f6a0 EFLAGS: 00010246
[ 3929.470042] RAX: 00000000000002de RBX: 0000000058a59000 RCX: 00000000000002df
[ 3929.470406] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff821f7020
[ 3929.470770] RBP: ffff88005872f6e8 R08: 000000000001f010 R09: 0000000000000000
[ 3929.471133] R10: ffff88005872f730 R11: 0000000000008cdd R12: ff006d75646d7564
[ 3929.471496] R13: 00000000014000c0 R14: ffff88005b403c00 R15: ffff88005b403c00
[ 3929.471869] FS:  00007f0b70480740(0000) GS:ffff88005d980000(0000) knlGS:0000000000000000
[ 3929.472286] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3929.472677] CR2: 00007ffcee4f3000 CR3: 0000000059d45000 CR4: 00000000000406e0
[ 3929.473209] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 3929.474109] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 3929.474873] Call Trace:
[ 3929.475337]  ? kstrdup_const+0x23/0x25
[ 3929.475863]  kstrdup+0x2e/0x4b
[ 3929.476338]  kstrdup_const+0x23/0x25
[ 3929.478084]  __kernfs_new_node+0x28/0xbc
[ 3929.478478]  kernfs_new_node+0x35/0x55
[ 3929.478929]  kernfs_create_link+0x23/0x76
[ 3929.479478]  sysfs_do_create_link_sd.isra.2+0x85/0xd7
[ 3929.480096]  sysfs_create_link+0x33/0x35
[ 3929.480649]  device_add+0x200/0x589
[ 3929.481184]  netdev_register_kobject+0x7c/0x12f
[ 3929.481711]  register_netdevice+0x373/0x471
[ 3929.482174]  rtnl_newlink+0x614/0x729
[ 3929.482610]  ? rtnl_newlink+0x17f/0x729
[ 3929.483080]  rtnetlink_rcv_msg+0x188/0x197
[ 3929.483533]  ? rcu_read_unlock+0x3e/0x5f
[ 3929.483984]  ? rtnl_newlink+0x729/0x729
[ 3929.484420]  netlink_rcv_skb+0x6c/0xce
[ 3929.484858]  rtnetlink_rcv+0x23/0x2a
[ 3929.485291]  netlink_unicast+0x103/0x181
[ 3929.485735]  netlink_sendmsg+0x326/0x337
[ 3929.486181]  sock_sendmsg_nosec+0x14/0x3f
[ 3929.486614]  sock_sendmsg+0x29/0x2e
[ 3929.486973]  ___sys_sendmsg+0x209/0x28b
[ 3929.487340]  ? do_raw_spin_unlock+0xcd/0xf8
[ 3929.487719]  ? _raw_spin_unlock+0x27/0x31
[ 3929.488092]  ? __handle_mm_fault+0x651/0xdb1
[ 3929.488471]  ? check_chain_key+0xb0/0xfd
[ 3929.488847]  __sys_sendmsg+0x45/0x63
[ 3929.489206]  ? __sys_sendmsg+0x45/0x63
[ 3929.489576]  SyS_sendmsg+0x19/0x1b
[ 3929.489901]  entry_SYSCALL_64_fastpath+0x23/0xc2
[ 3929.490172] RIP: 0033:0x7f0b6fb93690
[ 3929.490423] RSP: 002b:00007ffcee4ed588 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 3929.490881] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007f0b6fb93690
[ 3929.491198] RDX: 0000000000000000 RSI: 00007ffcee4ed5d0 RDI: 0000000000000003
[ 3929.491521] RBP: ffff88005872ff98 R08: 0000000000000001 R09: 0000000000000000
[ 3929.491801] R10: 00007ffcee4ed350 R11: 0000000000000246 R12: 0000000000000002
[ 3929.492075] R13: 000000000066f1a0 R14: 00007ffcee4f5680 R15: 0000000000000000
[ 3929.492352]  ? trace_hardirqs_off_caller+0xa7/0xcf
[ 3929.492590] Code: 8b 45 c0 48 8b 45 b8 74 17 48 8b 4d c8 83 ca ff 44
89 ee 4c 89 f7 e8 83 ca ff ff 49 89 c4 eb 49 49 63 56 20 48 8d 48 01 4d
8b 06 <49> 8b 1c 14 48 89 c2 4c 89 e0 65 49 0f c7 08 0f 94 c0 83 f0 01
[ 3929.493335] RIP: __kmalloc_track_caller+0x117/0x1be RSP: ffff88005872f6a0

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Fixes: f07d1501292b ("multiq: Further multiqueue cleanup")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_multiq.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/net/sched/sch_multiq.c b/net/sched/sch_multiq.c
index f143b7bbaa0d..9c454f5d6c38 100644
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -257,12 +257,7 @@ static int multiq_init(struct Qdisc *sch, struct nlattr *opt)
 	for (i = 0; i < q->max_bands; i++)
 		q->queues[i] = &noop_qdisc;
 
-	err = multiq_tune(sch, opt);
-
-	if (err)
-		kfree(q->queues);
-
-	return err;
+	return multiq_tune(sch, opt);
 }
 
 static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)
-- 
2.1.4

[PATCH net 3/9] sch_hhf: fix null pointer dereference on init failure

[Nikolay Aleksandrov]

If sch_hhf fails in its ->init() function (either due to wrong
user-space arguments as below or memory alloc failure of hh_flows) it
will do a null pointer deref of q->hh_flows in its ->destroy() function.

To reproduce the crash:
$ tc qdisc add dev eth0 root hhf quantum 2000000 non_hh_weight 10000000

Crash log:
[  690.654882] BUG: unable to handle kernel NULL pointer dereference at (null)
[  690.655565] IP: hhf_destroy+0x48/0xbc
[  690.655944] PGD 37345067
[  690.655948] P4D 37345067
[  690.656252] PUD 58402067
[  690.656554] PMD 0
[  690.656857]
[  690.657362] Oops: 0000 [#1] SMP
[  690.657696] Modules linked in:
[  690.658032] CPU: 3 PID: 920 Comm: tc Not tainted 4.13.0-rc6+ #57
[  690.658525] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[  690.659255] task: ffff880058578000 task.stack: ffff88005acbc000
[  690.659747] RIP: 0010:hhf_destroy+0x48/0xbc
[  690.660146] RSP: 0018:ffff88005acbf9e0 EFLAGS: 00010246
[  690.660601] RAX: 0000000000000000 RBX: 0000000000000020 RCX: 0000000000000000
[  690.661155] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff821f63f0
[  690.661710] RBP: ffff88005acbfa08 R08: ffffffff81b10a90 R09: 0000000000000000
[  690.662267] R10: 00000000f42b7019 R11: ffff880058578000 R12: 00000000ffffffea
[  690.662820] R13: ffff8800372f6400 R14: 0000000000000000 R15: 0000000000000000
[  690.663769] FS:  00007f8ae5e8b740(0000) GS:ffff88005d980000(0000) knlGS:0000000000000000
[  690.667069] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  690.667965] CR2: 0000000000000000 CR3: 0000000058523000 CR4: 00000000000406e0
[  690.668918] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  690.669945] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  690.671003] Call Trace:
[  690.671743]  qdisc_create+0x377/0x3fd
[  690.672534]  tc_modify_qdisc+0x4d2/0x4fd
[  690.673324]  rtnetlink_rcv_msg+0x188/0x197
[  690.674204]  ? rcu_read_unlock+0x3e/0x5f
[  690.675091]  ? rtnl_newlink+0x729/0x729
[  690.675877]  netlink_rcv_skb+0x6c/0xce
[  690.676648]  rtnetlink_rcv+0x23/0x2a
[  690.677405]  netlink_unicast+0x103/0x181
[  690.678179]  netlink_sendmsg+0x326/0x337
[  690.678958]  sock_sendmsg_nosec+0x14/0x3f
[  690.679743]  sock_sendmsg+0x29/0x2e
[  690.680506]  ___sys_sendmsg+0x209/0x28b
[  690.681283]  ? __handle_mm_fault+0xc7d/0xdb1
[  690.681915]  ? check_chain_key+0xb0/0xfd
[  690.682449]  __sys_sendmsg+0x45/0x63
[  690.682954]  ? __sys_sendmsg+0x45/0x63
[  690.683471]  SyS_sendmsg+0x19/0x1b
[  690.683974]  entry_SYSCALL_64_fastpath+0x23/0xc2
[  690.684516] RIP: 0033:0x7f8ae529d690
[  690.685016] RSP: 002b:00007fff26d2d6b8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[  690.685931] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007f8ae529d690
[  690.686573] RDX: 0000000000000000 RSI: 00007fff26d2d700 RDI: 0000000000000003
[  690.687047] RBP: ffff88005acbff98 R08: 0000000000000001 R09: 0000000000000000
[  690.687519] R10: 00007fff26d2d480 R11: 0000000000000246 R12: 0000000000000002
[  690.687996] R13: 0000000001258070 R14: 0000000000000001 R15: 0000000000000000
[  690.688475]  ? trace_hardirqs_off_caller+0xa7/0xcf
[  690.688887] Code: 00 00 e8 2a 02 ae ff 49 8b bc 1d 60 02 00 00 48 83
c3 08 e8 19 02 ae ff 48 83 fb 20 75 dc 45 31 f6 4d 89 f7 4d 03 bd 20 02
00 00 <49> 8b 07 49 39 c7 75 24 49 83 c6 10 49 81 fe 00 40 00 00 75 e1
[  690.690200] RIP: hhf_destroy+0x48/0xbc RSP: ffff88005acbf9e0
[  690.690636] CR2: 0000000000000000

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Fixes: 10239edf86f1 ("net-qdisc-hhf: Heavy-Hitter Filter (HHF) qdisc")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_hhf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/sched/sch_hhf.c b/net/sched/sch_hhf.c
index 51d3ba682af9..73a53c08091b 100644
--- a/net/sched/sch_hhf.c
+++ b/net/sched/sch_hhf.c
@@ -477,6 +477,9 @@ static void hhf_destroy(struct Qdisc *sch)
 		kvfree(q->hhf_valid_bits[i]);
 	}
 
+	if (!q->hh_flows)
+		return;
+
 	for (i = 0; i < HH_FLOWS_CNT; i++) {
 		struct hh_flow_state *flow, *next;
 		struct list_head *head = &q->hh_flows[i];
-- 
2.1.4

[PATCH net 4/9] sch_hfsc: fix null pointer deref and double free on init failure

[Nikolay Aleksandrov]

Depending on where ->init fails we can get a null pointer deref due to
uninitialized hires timer (watchdog) or a double free of the qdisc hash
because it is already freed by ->destroy().

Fixes: 8d5537387505 ("net/sched/hfsc: allocate tcf block for hfsc root class")
Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_hfsc.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index fd15200f8627..11ab8dace901 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1418,6 +1418,8 @@ hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 	struct tc_hfsc_qopt *qopt;
 	int err;
 
+	qdisc_watchdog_init(&q->watchdog, sch);
+
 	if (opt == NULL || nla_len(opt) < sizeof(*qopt))
 		return -EINVAL;
 	qopt = nla_data(opt);
@@ -1430,7 +1432,7 @@ hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 
 	err = tcf_block_get(&q->root.block, &q->root.filter_list);
 	if (err)
-		goto err_tcf;
+		return err;
 
 	q->root.cl_common.classid = sch->handle;
 	q->root.refcnt  = 1;
@@ -1448,13 +1450,7 @@ hfsc_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
 	qdisc_class_hash_insert(&q->clhash, &q->root.cl_common);
 	qdisc_class_hash_grow(sch, &q->clhash);
 
-	qdisc_watchdog_init(&q->watchdog, sch);
-
 	return 0;
-
-err_tcf:
-	qdisc_class_hash_destroy(&q->clhash);
-	return err;
 }
 
 static int
-- 
2.1.4

[PATCH net 5/9] sch_cbq: fix null pointer dereferences on init failure

[Nikolay Aleksandrov]

CBQ can fail on ->init by wrong nl attributes or simply for missing any,
f.e. if it's set as a default qdisc then TCA_OPTIONS (opt) will be NULL
when it is activated. The first thing init does is parse opt but it will
dereference a null pointer if used as a default qdisc, also since init
failure at default qdisc invokes ->reset() which cancels all timers then
we'll also dereference two more null pointers (timer->base) as they were
never initialized.

To reproduce:
$ sysctl net.core.default_qdisc=cbq
$ ip l set ethX up

Crash log of the first null ptr deref:
[44727.907454] BUG: unable to handle kernel NULL pointer dereference at (null)
[44727.907600] IP: cbq_init+0x27/0x205
[44727.907676] PGD 59ff4067
[44727.907677] P4D 59ff4067
[44727.907742] PUD 59c70067
[44727.907807] PMD 0
[44727.907873]
[44727.907982] Oops: 0000 [#1] SMP
[44727.908054] Modules linked in:
[44727.908126] CPU: 1 PID: 21312 Comm: ip Not tainted 4.13.0-rc6+ #60
[44727.908235] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[44727.908477] task: ffff88005ad42700 task.stack: ffff880037214000
[44727.908672] RIP: 0010:cbq_init+0x27/0x205
[44727.908838] RSP: 0018:ffff8800372175f0 EFLAGS: 00010286
[44727.909018] RAX: ffffffff816c3852 RBX: ffff880058c53800 RCX: 0000000000000000
[44727.909222] RDX: 0000000000000004 RSI: 0000000000000000 RDI: ffff8800372175f8
[44727.909427] RBP: ffff880037217650 R08: ffffffff81b0f380 R09: 0000000000000000
[44727.909631] R10: ffff880037217660 R11: 0000000000000020 R12: ffffffff822a44c0
[44727.909835] R13: ffff880058b92000 R14: 00000000ffffffff R15: 0000000000000001
[44727.910040] FS:  00007ff8bc583740(0000) GS:ffff88005d880000(0000) knlGS:0000000000000000
[44727.910339] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[44727.910525] CR2: 0000000000000000 CR3: 00000000371e5000 CR4: 00000000000406e0
[44727.910731] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[44727.910936] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[44727.911141] Call Trace:
[44727.911291]  ? lockdep_init_map+0xb6/0x1ba
[44727.911461]  ? qdisc_alloc+0x14e/0x187
[44727.911626]  qdisc_create_dflt+0x7a/0x94
[44727.911794]  ? dev_activate+0x129/0x129
[44727.911959]  attach_one_default_qdisc+0x36/0x63
[44727.912132]  netdev_for_each_tx_queue+0x3d/0x48
[44727.912305]  dev_activate+0x4b/0x129
[44727.912468]  __dev_open+0xe7/0x104
[44727.912631]  __dev_change_flags+0xc6/0x15c
[44727.912799]  dev_change_flags+0x25/0x59
[44727.912966]  do_setlink+0x30c/0xb3f
[44727.913129]  ? check_chain_key+0xb0/0xfd
[44727.913294]  ? check_chain_key+0xb0/0xfd
[44727.913463]  rtnl_newlink+0x3a4/0x729
[44727.913626]  ? rtnl_newlink+0x117/0x729
[44727.913801]  ? ns_capable_common+0xd/0xb1
[44727.913968]  ? ns_capable+0x13/0x15
[44727.914131]  rtnetlink_rcv_msg+0x188/0x197
[44727.914300]  ? rcu_read_unlock+0x3e/0x5f
[44727.914465]  ? rtnl_newlink+0x729/0x729
[44727.914630]  netlink_rcv_skb+0x6c/0xce
[44727.914796]  rtnetlink_rcv+0x23/0x2a
[44727.914956]  netlink_unicast+0x103/0x181
[44727.915122]  netlink_sendmsg+0x326/0x337
[44727.915291]  sock_sendmsg_nosec+0x14/0x3f
[44727.915459]  sock_sendmsg+0x29/0x2e
[44727.915619]  ___sys_sendmsg+0x209/0x28b
[44727.915784]  ? do_raw_spin_unlock+0xcd/0xf8
[44727.915954]  ? _raw_spin_unlock+0x27/0x31
[44727.916121]  ? __handle_mm_fault+0x651/0xdb1
[44727.916290]  ? check_chain_key+0xb0/0xfd
[44727.916461]  __sys_sendmsg+0x45/0x63
[44727.916626]  ? __sys_sendmsg+0x45/0x63
[44727.916792]  SyS_sendmsg+0x19/0x1b
[44727.916950]  entry_SYSCALL_64_fastpath+0x23/0xc2
[44727.917125] RIP: 0033:0x7ff8bbc96690
[44727.917286] RSP: 002b:00007ffc360991e8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[44727.917579] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007ff8bbc96690
[44727.917783] RDX: 0000000000000000 RSI: 00007ffc36099230 RDI: 0000000000000003
[44727.917987] RBP: ffff880037217f98 R08: 0000000000000001 R09: 0000000000000003
[44727.918190] R10: 00007ffc36098fb0 R11: 0000000000000246 R12: 0000000000000006
[44727.918393] R13: 000000000066f1a0 R14: 00007ffc360a12e0 R15: 0000000000000000
[44727.918597]  ? trace_hardirqs_off_caller+0xa7/0xcf
[44727.918774] Code: 41 5f 5d c3 66 66 66 66 90 55 48 8d 56 04 45 31 c9
49 c7 c0 80 f3 b0 81 48 89 e5 41 55 41 54 53 48 89 fb 48 8d 7d a8 48 83
ec 48 <0f> b7 0e be 07 00 00 00 83 e9 04 e8 e6 f7 d8 ff 85 c0 0f 88 bb
[44727.919332] RIP: cbq_init+0x27/0x205 RSP: ffff8800372175f0
[44727.919516] CR2: 0000000000000000

Fixes: 0fbbeb1ba43b ("[PKT_SCHED]: Fix missing qdisc_destroy() in qdisc_create_dflt()")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_cbq.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 780db43300b1..156c8a33c677 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1139,6 +1139,13 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt)
 	struct tc_ratespec *r;
 	int err;
 
+	qdisc_watchdog_init(&q->watchdog, sch);
+	hrtimer_init(&q->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
+	q->delay_timer.function = cbq_undelay;
+
+	if (!opt)
+		return -EINVAL;
+
 	err = nla_parse_nested(tb, TCA_CBQ_MAX, opt, cbq_policy, NULL);
 	if (err < 0)
 		return err;
@@ -1177,9 +1184,6 @@ static int cbq_init(struct Qdisc *sch, struct nlattr *opt)
 	q->link.avpkt = q->link.allot/2;
 	q->link.minidle = -0x7FFFFFFF;
 
-	qdisc_watchdog_init(&q->watchdog, sch);
-	hrtimer_init(&q->delay_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
-	q->delay_timer.function = cbq_undelay;
 	q->toplevel = TC_CBQ_MAXLEVEL;
 	q->now = psched_get_time();
 
-- 
2.1.4

[PATCH net 6/9] sch_fq_codel: avoid double free on init failure

[Nikolay Aleksandrov]

It is very unlikely to happen but the backlogs memory allocation
could fail and will free q->flows, but then ->destroy() will free
q->flows too. For correctness remove the first free and let ->destroy
clean up.

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_fq_codel.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 337f2d6d81e4..2c0c05f2cc34 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -491,10 +491,8 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
 		if (!q->flows)
 			return -ENOMEM;
 		q->backlogs = kvzalloc(q->flows_cnt * sizeof(u32), GFP_KERNEL);
-		if (!q->backlogs) {
-			kvfree(q->flows);
+		if (!q->backlogs)
 			return -ENOMEM;
-		}
 		for (i = 0; i < q->flows_cnt; i++) {
 			struct fq_codel_flow *flow = q->flows + i;
 
-- 
2.1.4

Re: [PATCH net 6/9] sch_fq_codel: avoid double free on init failure

[Cong Wang]

On Wed, Aug 30, 2017 at 2:49 AM, Nikolay Aleksandrov
<nikolay@cumulusnetworks.com> wrote:
> It is very unlikely to happen but the backlogs memory allocation
> could fail and will free q->flows, but then ->destroy() will free
> q->flows too. For correctness remove the first free and let ->destroy
> clean up.
>
> Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> ---
>  net/sched/sch_fq_codel.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
> index 337f2d6d81e4..2c0c05f2cc34 100644
> --- a/net/sched/sch_fq_codel.c
> +++ b/net/sched/sch_fq_codel.c
> @@ -491,10 +491,8 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
>                 if (!q->flows)
>                         return -ENOMEM;
>                 q->backlogs = kvzalloc(q->flows_cnt * sizeof(u32), GFP_KERNEL);
> -               if (!q->backlogs) {
> -                       kvfree(q->flows);
> +               if (!q->backlogs)
>                         return -ENOMEM;
> -               }

This is fine. Or we can NULL it after kvfree().

I have no preference here. The only difference here is if we still
expect ->init() to cleanup its own failure.

Re: [PATCH net 6/9] sch_fq_codel: avoid double free on init failure

[Nikolay Aleksandrov]

On 30/08/17 20:36, Cong Wang wrote:
> On Wed, Aug 30, 2017 at 2:49 AM, Nikolay Aleksandrov
> <nikolay@cumulusnetworks.com> wrote:
>> It is very unlikely to happen but the backlogs memory allocation
>> could fail and will free q->flows, but then ->destroy() will free
>> q->flows too. For correctness remove the first free and let ->destroy
>> clean up.
>>
>> Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
>> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
>> ---
>>  net/sched/sch_fq_codel.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
>> index 337f2d6d81e4..2c0c05f2cc34 100644
>> --- a/net/sched/sch_fq_codel.c
>> +++ b/net/sched/sch_fq_codel.c
>> @@ -491,10 +491,8 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt)
>>                 if (!q->flows)
>>                         return -ENOMEM;
>>                 q->backlogs = kvzalloc(q->flows_cnt * sizeof(u32), GFP_KERNEL);
>> -               if (!q->backlogs) {
>> -                       kvfree(q->flows);
>> +               if (!q->backlogs)
>>                         return -ENOMEM;
>> -               }
> 
> This is fine. Or we can NULL it after kvfree().
> 
> I have no preference here. The only difference here is if we still
> expect ->init() to cleanup its own failure.
> 

We don't, that's the point of the changes that lead to these fixes,
the way ->destroy() is used by both the default qdisc infra and the
normal qdisc add suggest that it should clean up after ->init failure,
thus the change.

[PATCH net 7/9] sch_netem: avoid null pointer deref on init failure

[Nikolay Aleksandrov]

netem can fail in ->init due to missing options (either not supplied by
user-space or used as a default qdisc) causing a timer->base null
pointer deref in its ->destroy() and ->reset() callbacks.

Reproduce:
$ sysctl net.core.default_qdisc=netem
$ ip l set ethX up

Crash log:
[ 1814.846943] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 1814.847181] IP: hrtimer_active+0x17/0x8a
[ 1814.847270] PGD 59c34067
[ 1814.847271] P4D 59c34067
[ 1814.847337] PUD 37374067
[ 1814.847403] PMD 0
[ 1814.847468]
[ 1814.847582] Oops: 0000 [#1] SMP
[ 1814.847655] Modules linked in: sch_netem(O) sch_fq_codel(O)
[ 1814.847761] CPU: 3 PID: 1573 Comm: ip Tainted: G           O 4.13.0-rc6+ #62
[ 1814.847884] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[ 1814.848043] task: ffff88003723a700 task.stack: ffff88005adc8000
[ 1814.848235] RIP: 0010:hrtimer_active+0x17/0x8a
[ 1814.848407] RSP: 0018:ffff88005adcb590 EFLAGS: 00010246
[ 1814.848590] RAX: 0000000000000000 RBX: ffff880058e359d8 RCX: 0000000000000000
[ 1814.848793] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880058e359d8
[ 1814.848998] RBP: ffff88005adcb5b0 R08: 00000000014080c0 R09: 00000000ffffffff
[ 1814.849204] R10: ffff88005adcb660 R11: 0000000000000020 R12: 0000000000000000
[ 1814.849410] R13: ffff880058e359d8 R14: 00000000ffffffff R15: 0000000000000001
[ 1814.849616] FS:  00007f733bbca740(0000) GS:ffff88005d980000(0000) knlGS:0000000000000000
[ 1814.849919] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1814.850107] CR2: 0000000000000000 CR3: 0000000059f0d000 CR4: 00000000000406e0
[ 1814.850313] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1814.850518] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1814.850723] Call Trace:
[ 1814.850875]  hrtimer_try_to_cancel+0x1a/0x93
[ 1814.851047]  hrtimer_cancel+0x15/0x20
[ 1814.851211]  qdisc_watchdog_cancel+0x12/0x14
[ 1814.851383]  netem_reset+0xe6/0xed [sch_netem]
[ 1814.851561]  qdisc_destroy+0x8b/0xe5
[ 1814.851723]  qdisc_create_dflt+0x86/0x94
[ 1814.851890]  ? dev_activate+0x129/0x129
[ 1814.852057]  attach_one_default_qdisc+0x36/0x63
[ 1814.852232]  netdev_for_each_tx_queue+0x3d/0x48
[ 1814.852406]  dev_activate+0x4b/0x129
[ 1814.852569]  __dev_open+0xe7/0x104
[ 1814.852730]  __dev_change_flags+0xc6/0x15c
[ 1814.852899]  dev_change_flags+0x25/0x59
[ 1814.853064]  do_setlink+0x30c/0xb3f
[ 1814.853228]  ? check_chain_key+0xb0/0xfd
[ 1814.853396]  ? check_chain_key+0xb0/0xfd
[ 1814.853565]  rtnl_newlink+0x3a4/0x729
[ 1814.853728]  ? rtnl_newlink+0x117/0x729
[ 1814.853905]  ? ns_capable_common+0xd/0xb1
[ 1814.854072]  ? ns_capable+0x13/0x15
[ 1814.854234]  rtnetlink_rcv_msg+0x188/0x197
[ 1814.854404]  ? rcu_read_unlock+0x3e/0x5f
[ 1814.854572]  ? rtnl_newlink+0x729/0x729
[ 1814.854737]  netlink_rcv_skb+0x6c/0xce
[ 1814.854902]  rtnetlink_rcv+0x23/0x2a
[ 1814.855064]  netlink_unicast+0x103/0x181
[ 1814.855230]  netlink_sendmsg+0x326/0x337
[ 1814.855398]  sock_sendmsg_nosec+0x14/0x3f
[ 1814.855584]  sock_sendmsg+0x29/0x2e
[ 1814.855747]  ___sys_sendmsg+0x209/0x28b
[ 1814.855912]  ? do_raw_spin_unlock+0xcd/0xf8
[ 1814.856082]  ? _raw_spin_unlock+0x27/0x31
[ 1814.856251]  ? __handle_mm_fault+0x651/0xdb1
[ 1814.856421]  ? check_chain_key+0xb0/0xfd
[ 1814.856592]  __sys_sendmsg+0x45/0x63
[ 1814.856755]  ? __sys_sendmsg+0x45/0x63
[ 1814.856923]  SyS_sendmsg+0x19/0x1b
[ 1814.857083]  entry_SYSCALL_64_fastpath+0x23/0xc2
[ 1814.857256] RIP: 0033:0x7f733b2dd690
[ 1814.857419] RSP: 002b:00007ffe1d3387d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 1814.858238] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007f733b2dd690
[ 1814.858445] RDX: 0000000000000000 RSI: 00007ffe1d338820 RDI: 0000000000000003
[ 1814.858651] RBP: ffff88005adcbf98 R08: 0000000000000001 R09: 0000000000000003
[ 1814.858856] R10: 00007ffe1d3385a0 R11: 0000000000000246 R12: 0000000000000002
[ 1814.859060] R13: 000000000066f1a0 R14: 00007ffe1d3408d0 R15: 0000000000000000
[ 1814.859267]  ? trace_hardirqs_off_caller+0xa7/0xcf
[ 1814.859446] Code: 10 55 48 89 c7 48 89 e5 e8 45 a1 fb ff 31 c0 5d c3
31 c0 c3 66 66 66 66 90 55 48 89 e5 41 56 41 55 41 54 53 49 89 fd 49 8b
45 30 <4c> 8b 20 41 8b 5c 24 38 31 c9 31 d2 48 c7 c7 50 8e 1d 82 41 89
[ 1814.860022] RIP: hrtimer_active+0x17/0x8a RSP: ffff88005adcb590
[ 1814.860214] CR2: 0000000000000000

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Fixes: 0fbbeb1ba43b ("[PKT_SCHED]: Fix missing qdisc_destroy() in qdisc_create_dflt()")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_netem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 1b3dd6190e93..14d1724e0dc4 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -933,11 +933,11 @@ static int netem_init(struct Qdisc *sch, struct nlattr *opt)
 	struct netem_sched_data *q = qdisc_priv(sch);
 	int ret;
 
+	qdisc_watchdog_init(&q->watchdog, sch);
+
 	if (!opt)
 		return -EINVAL;
 
-	qdisc_watchdog_init(&q->watchdog, sch);
-
 	q->loss_model = CLG_RANDOM;
 	ret = netem_change(sch, opt);
 	if (ret)
-- 
2.1.4

[PATCH net 8/9] sch_sfq: fix null pointer dereference on init failure

[Nikolay Aleksandrov]

Currently only a memory allocation failure can lead to this, so let's
initialize the timer first.

Fixes: 6529eaba33f0 ("net: sched: introduce tcf block infractructure")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_sfq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 82469ef9655e..fc69fc5956e9 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -716,13 +716,13 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
 	int i;
 	int err;
 
+	setup_deferrable_timer(&q->perturb_timer, sfq_perturbation,
+			       (unsigned long)sch);
+
 	err = tcf_block_get(&q->block, &q->filter_list);
 	if (err)
 		return err;
 
-	setup_deferrable_timer(&q->perturb_timer, sfq_perturbation,
-			       (unsigned long)sch);
-
 	for (i = 0; i < SFQ_MAX_DEPTH + 1; i++) {
 		q->dep[i].next = i + SFQ_MAX_FLOWS;
 		q->dep[i].prev = i + SFQ_MAX_FLOWS;
-- 
2.1.4

[PATCH net 9/9] sch_tbf: fix two null pointer dereferences on init failure

[Nikolay Aleksandrov]

sch_tbf calls qdisc_watchdog_cancel() in both its ->reset and ->destroy
callbacks but it may fail before the timer is initialized due to missing
options (either not supplied by user-space or set as a default qdisc),
also q->qdisc is used by ->reset and ->destroy so we need it initialized.

Reproduce:
$ sysctl net.core.default_qdisc=tbf
$ ip l set ethX up

Crash log:
[  959.160172] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
[  959.160323] IP: qdisc_reset+0xa/0x5c
[  959.160400] PGD 59cdb067
[  959.160401] P4D 59cdb067
[  959.160466] PUD 59ccb067
[  959.160532] PMD 0
[  959.160597]
[  959.160706] Oops: 0000 [#1] SMP
[  959.160778] Modules linked in: sch_tbf sch_sfb sch_prio sch_netem
[  959.160891] CPU: 2 PID: 1562 Comm: ip Not tainted 4.13.0-rc6+ #62
[  959.160998] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140531_083030-gandalf 04/01/2014
[  959.161157] task: ffff880059c9a700 task.stack: ffff8800376d0000
[  959.161263] RIP: 0010:qdisc_reset+0xa/0x5c
[  959.161347] RSP: 0018:ffff8800376d3610 EFLAGS: 00010286
[  959.161531] RAX: ffffffffa001b1dd RBX: ffff8800373a2800 RCX: 0000000000000000
[  959.161733] RDX: ffffffff8215f160 RSI: ffffffff8215f160 RDI: 0000000000000000
[  959.161939] RBP: ffff8800376d3618 R08: 00000000014080c0 R09: 00000000ffffffff
[  959.162141] R10: ffff8800376d3578 R11: 0000000000000020 R12: ffffffffa001d2c0
[  959.162343] R13: ffff880037538000 R14: 00000000ffffffff R15: 0000000000000001
[  959.162546] FS:  00007fcc5126b740(0000) GS:ffff88005d900000(0000) knlGS:0000000000000000
[  959.162844] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  959.163030] CR2: 0000000000000018 CR3: 000000005abc4000 CR4: 00000000000406e0
[  959.163233] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  959.163436] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  959.163638] Call Trace:
[  959.163788]  tbf_reset+0x19/0x64 [sch_tbf]
[  959.163957]  qdisc_destroy+0x8b/0xe5
[  959.164119]  qdisc_create_dflt+0x86/0x94
[  959.164284]  ? dev_activate+0x129/0x129
[  959.164449]  attach_one_default_qdisc+0x36/0x63
[  959.164623]  netdev_for_each_tx_queue+0x3d/0x48
[  959.164795]  dev_activate+0x4b/0x129
[  959.164957]  __dev_open+0xe7/0x104
[  959.165118]  __dev_change_flags+0xc6/0x15c
[  959.165287]  dev_change_flags+0x25/0x59
[  959.165451]  do_setlink+0x30c/0xb3f
[  959.165613]  ? check_chain_key+0xb0/0xfd
[  959.165782]  rtnl_newlink+0x3a4/0x729
[  959.165947]  ? rtnl_newlink+0x117/0x729
[  959.166121]  ? ns_capable_common+0xd/0xb1
[  959.166288]  ? ns_capable+0x13/0x15
[  959.166450]  rtnetlink_rcv_msg+0x188/0x197
[  959.166617]  ? rcu_read_unlock+0x3e/0x5f
[  959.166783]  ? rtnl_newlink+0x729/0x729
[  959.166948]  netlink_rcv_skb+0x6c/0xce
[  959.167113]  rtnetlink_rcv+0x23/0x2a
[  959.167273]  netlink_unicast+0x103/0x181
[  959.167439]  netlink_sendmsg+0x326/0x337
[  959.167607]  sock_sendmsg_nosec+0x14/0x3f
[  959.167772]  sock_sendmsg+0x29/0x2e
[  959.167932]  ___sys_sendmsg+0x209/0x28b
[  959.168098]  ? do_raw_spin_unlock+0xcd/0xf8
[  959.168267]  ? _raw_spin_unlock+0x27/0x31
[  959.168432]  ? __handle_mm_fault+0x651/0xdb1
[  959.168602]  ? check_chain_key+0xb0/0xfd
[  959.168773]  __sys_sendmsg+0x45/0x63
[  959.168934]  ? __sys_sendmsg+0x45/0x63
[  959.169100]  SyS_sendmsg+0x19/0x1b
[  959.169260]  entry_SYSCALL_64_fastpath+0x23/0xc2
[  959.169432] RIP: 0033:0x7fcc5097e690
[  959.169592] RSP: 002b:00007ffd0d5c7b48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[  959.169887] RAX: ffffffffffffffda RBX: ffffffff810d278c RCX: 00007fcc5097e690
[  959.170089] RDX: 0000000000000000 RSI: 00007ffd0d5c7b90 RDI: 0000000000000003
[  959.170292] RBP: ffff8800376d3f98 R08: 0000000000000001 R09: 0000000000000003
[  959.170494] R10: 00007ffd0d5c7910 R11: 0000000000000246 R12: 0000000000000006
[  959.170697] R13: 000000000066f1a0 R14: 00007ffd0d5cfc40 R15: 0000000000000000
[  959.170900]  ? trace_hardirqs_off_caller+0xa7/0xcf
[  959.171076] Code: 00 41 c7 84 24 14 01 00 00 00 00 00 00 41 c7 84 24
98 00 00 00 00 00 00 00 41 5c 41 5d 41 5e 5d c3 66 66 66 66 90 55 48 89
e5 53 <48> 8b 47 18 48 89 fb 48 8b 40 48 48 85 c0 74 02 ff d0 48 8b bb
[  959.171637] RIP: qdisc_reset+0xa/0x5c RSP: ffff8800376d3610
[  959.171821] CR2: 0000000000000018

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Fixes: 0fbbeb1ba43b ("[PKT_SCHED]: Fix missing qdisc_destroy() in qdisc_create_dflt()")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
---
 net/sched/sch_tbf.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index b2e4b6ad241a..493270f0d5b0 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -425,12 +425,13 @@ static int tbf_init(struct Qdisc *sch, struct nlattr *opt)
 {
 	struct tbf_sched_data *q = qdisc_priv(sch);
 
+	qdisc_watchdog_init(&q->watchdog, sch);
+	q->qdisc = &noop_qdisc;
+
 	if (opt == NULL)
 		return -EINVAL;
 
 	q->t_c = ktime_get_ns();
-	qdisc_watchdog_init(&q->watchdog, sch);
-	q->qdisc = &noop_qdisc;
 
 	return tbf_change(sch, opt);
 }
-- 
2.1.4

Re: [PATCH net 9/9] sch_tbf: fix two null pointer dereferences on init failure

[Cong Wang]

On Wed, Aug 30, 2017 at 2:49 AM, Nikolay Aleksandrov
<nikolay@cumulusnetworks.com> wrote:
> Reproduce:
> $ sysctl net.core.default_qdisc=tbf
> $ ip l set ethX up

I once upon a time had a patch to disallow those qdisc's
to be default. Probably I should resend it.

Re: [PATCH net 9/9] sch_tbf: fix two null pointer dereferences on init failure

[Nikolay Aleksandrov]

On 30/08/17 20:37, Cong Wang wrote:
> On Wed, Aug 30, 2017 at 2:49 AM, Nikolay Aleksandrov
> <nikolay@cumulusnetworks.com> wrote:
>> Reproduce:
>> $ sysctl net.core.default_qdisc=tbf
>> $ ip l set ethX up
> 
> I once upon a time had a patch to disallow those qdisc's
> to be default. Probably I should resend it.
> 

That sounds good. A lot of them can't be default anyway, they need
some options to be set, so it's definitely worth looking into.

Re: [PATCH net 0/9] net/sched: init failure fixes

[Jamal Hadi Salim]

On 17-08-30 05:48 AM, Nikolay Aleksandrov wrote:
> Hi all,
> I went over all qdiscs' init, destroy and reset callbacks and found the
> issues fixed in each patch. Mostly they are null pointer dereferences due
> to uninitialized timer (qdisc watchdog) or double frees due to ->destroy
> cleaning up a second time. There's more information in each patch.
> I've tested these by either sending wrong attributes from user-spaces, no
> attributes or by simulating memory alloc failure where applicable. Also
> tried all of the qdiscs as a default qdisc.
> 
> Most of these bugs were present before commit 87b60cfacf9f, I've tried to
> include proper fixes tags in each patch.
> 
> I haven't included individual patch acks in the set, I'd appreciate it if
> you take another look and resend them.
> 


Hi Nik,

For all patches:

Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

Would you please consider adding all the the tests
you used to create the oopses in selftests? It will ensure this
embarassing bugs get caught should they ever happen again.
If you need help ping Lucas on Cc.

cheers,
jamal

Re: [PATCH net 0/9] net/sched: init failure fixes

[Nikolay Aleksandrov]

On 30/08/17 15:15, Jamal Hadi Salim wrote:
> On 17-08-30 05:48 AM, Nikolay Aleksandrov wrote:
>> Hi all,
>> I went over all qdiscs' init, destroy and reset callbacks and found the
>> issues fixed in each patch. Mostly they are null pointer dereferences due
>> to uninitialized timer (qdisc watchdog) or double frees due to ->destroy
>> cleaning up a second time. There's more information in each patch.
>> I've tested these by either sending wrong attributes from user-spaces, no
>> attributes or by simulating memory alloc failure where applicable. Also
>> tried all of the qdiscs as a default qdisc.
>>
>> Most of these bugs were present before commit 87b60cfacf9f, I've tried to
>> include proper fixes tags in each patch.
>>
>> I haven't included individual patch acks in the set, I'd appreciate it if
>> you take another look and resend them.
>>
> 
> 
> Hi Nik,
> 
> For all patches:
> 
> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
> 
> Would you please consider adding all the the tests
> you used to create the oopses in selftests? It will ensure this
> embarassing bugs get caught should they ever happen again.
> If you need help ping Lucas on Cc.
> 
> cheers,
> jamal

Hi,
Sure, I'll make the tests and send patches for tc selftests, using the infra at
tools/testing/selftests/tc-testing.

Thanks!

Re: [PATCH net 0/9] net/sched: init failure fixes

[David Miller]

From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Wed, 30 Aug 2017 08:15:37 -0400

> On 17-08-30 05:48 AM, Nikolay Aleksandrov wrote:
>> Hi all,
>> I went over all qdiscs' init, destroy and reset callbacks and found
>> the
>> issues fixed in each patch. Mostly they are null pointer dereferences
>> due
>> to uninitialized timer (qdisc watchdog) or double frees due to
>> ->destroy
>> cleaning up a second time. There's more information in each patch.
>> I've tested these by either sending wrong attributes from user-spaces,
>> no
>> attributes or by simulating memory alloc failure where
>> applicable. Also
>> tried all of the qdiscs as a default qdisc.
>> Most of these bugs were present before commit 87b60cfacf9f, I've tried
>> to
>> include proper fixes tags in each patch.
>> I haven't included individual patch acks in the set, I'd appreciate it
>> if
>> you take another look and resend them.
>> 
> 
> 
> Hi Nik,
> 
> For all patches:
> 
> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

Series applied, thanks Nikolay.