[PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()

[PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()

[yskelg]

From: Yunseong Kim <yskelg@gmail.com>

In the TRACE_EVENT(qdisc_reset) NULL dereference occurred from

 qdisc->dev_queue->dev <NULL> ->name

This situation simulated from bunch of veths and Bluetooth dis/reconnection.

During qdisc initialization, qdisc was being set to noop_queue.
In veth_init_queue, the initial tx_num was reduced back to one,
causing the qdisc reset to be called with noop, which led to the kernel panic.

I've attached the GitHub gist link that C converted syz-execprogram
source code and 3 log of reproduced vmcore-dmesg.

 https://gist.github.com/yskelg/cc64562873ce249cdd0d5a358b77d740

Yeoreum and I use two fuzzing tool simultaneously.

One process with syz-executor : https://github.com/google/syzkaller

 $ ./syz-execprog -executor=./syz-executor -repeat=1 -sandbox=setuid \
    -enable=none -collide=false log1

The other process with perf fuzzer:
 https://github.com/deater/perf_event_tests/tree/master/fuzzer

 $ perf_event_tests/fuzzer/perf_fuzzer

I think this will happen on the kernel version.

 Linux kernel version ≥ v6.7.10, ≥ v6.8 ≥ v6.9 and 6.10

This occurred from 51270d573a8d. I think this patch is absolutely 
necessary. Previously, It was showing not intended string value of name.

I've reproduced 3 time from my fedora 40 Debug Kernel with any other module 
or patched.

 version: 6.10.0-0.rc2.20240608gitdc772f8237f9.29.fc41.aarch64+debug

[ 5287.164555] veth0_vlan: left promiscuous mode
[ 5287.164929] veth1_macvtap: left promiscuous mode
[ 5287.164950] veth0_macvtap: left promiscuous mode
[ 5287.164983] veth1_vlan: left promiscuous mode
[ 5287.165008] veth0_vlan: left promiscuous mode
[ 5287.165450] veth1_macvtap: left promiscuous mode
[ 5287.165472] veth0_macvtap: left promiscuous mode
[ 5287.165502] veth1_vlan: left promiscuous mode
…
[ 5297.598240] bridge0: port 2(bridge_slave_1) entered blocking state
[ 5297.598262] bridge0: port 2(bridge_slave_1) entered forwarding state
[ 5297.598296] bridge0: port 1(bridge_slave_0) entered blocking state
[ 5297.598313] bridge0: port 1(bridge_slave_0) entered forwarding state
[ 5297.616090] 8021q: adding VLAN 0 to HW filter on device bond0
[ 5297.620405] bridge0: port 1(bridge_slave_0) entered disabled state
[ 5297.620730] bridge0: port 2(bridge_slave_1) entered disabled state
[ 5297.627247] 8021q: adding VLAN 0 to HW filter on device team0
[ 5297.629636] bridge0: port 1(bridge_slave_0) entered blocking state
…
[ 5298.002798] bridge_slave_0: left promiscuous mode
[ 5298.002869] bridge0: port 1(bridge_slave_0) entered disabled state
[ 5298.309444] bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
[ 5298.315206] bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
[ 5298.320207] bond0 (unregistering): Released all slaves
[ 5298.354296] hsr_slave_0: left promiscuous mode
[ 5298.360750] hsr_slave_1: left promiscuous mode
[ 5298.374889] veth1_macvtap: left promiscuous mode
[ 5298.374931] veth0_macvtap: left promiscuous mode
[ 5298.374988] veth1_vlan: left promiscuous mode
[ 5298.375024] veth0_vlan: left promiscuous mode
[ 5299.109741] team0 (unregistering): Port device team_slave_1 removed
[ 5299.185870] team0 (unregistering): Port device team_slave_0 removed
…
[ 5300.155443] Bluetooth: hci3: unexpected cc 0x0c03 length: 249 > 1
[ 5300.155724] Bluetooth: hci3: unexpected cc 0x1003 length: 249 > 9
[ 5300.155988] Bluetooth: hci3: unexpected cc 0x1001 length: 249 > 9
….
[ 5301.075531] team0: Port device team_slave_1 added
[ 5301.085515] bridge0: port 1(bridge_slave_0) entered blocking state
[ 5301.085531] bridge0: port 1(bridge_slave_0) entered disabled state
[ 5301.085588] bridge_slave_0: entered allmulticast mode
[ 5301.085800] bridge_slave_0: entered promiscuous mode
[ 5301.095617] bridge0: port 1(bridge_slave_0) entered blocking state
[ 5301.095633] bridge0: port 1(bridge_slave_0) entered disabled state
…
[ 5301.149734] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[ 5301.173234] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[ 5301.180517] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[ 5301.193481] hsr_slave_0: entered promiscuous mode
[ 5301.204425] hsr_slave_1: entered promiscuous mode
[ 5301.210172] debugfs: Directory 'hsr0' with parent 'hsr' already present!
[ 5301.210185] Cannot create hsr debugfs directory
[ 5301.224061] bond0: (slave bond_slave_1): Enslaving as an active interface with an up link
[ 5301.246901] bond0: (slave bond_slave_0): Enslaving as an active interface with an up link
[ 5301.255934] team0: Port device team_slave_0 added
[ 5301.256480] team0: Port device team_slave_1 added
[ 5301.256948] team0: Port device team_slave_0 added
…
[ 5301.435928] hsr_slave_0: entered promiscuous mode
[ 5301.446029] hsr_slave_1: entered promiscuous mode
[ 5301.455872] debugfs: Directory 'hsr0' with parent 'hsr' already present!
[ 5301.455884] Cannot create hsr debugfs directory
[ 5301.502664] hsr_slave_0: entered promiscuous mode
[ 5301.513675] hsr_slave_1: entered promiscuous mode
[ 5301.526155] debugfs: Directory 'hsr0' with parent 'hsr' already present!
[ 5301.526164] Cannot create hsr debugfs directory
[ 5301.563662] hsr_slave_0: entered promiscuous mode
[ 5301.576129] hsr_slave_1: entered promiscuous mode
[ 5301.580259] debugfs: Directory 'hsr0' with parent 'hsr' already present!
[ 5301.580270] Cannot create hsr debugfs directory
[ 5301.590269] 8021q: adding VLAN 0 to HW filter on device bond0

[ 5301.595872] KASAN: null-ptr-deref in range [0x0000000000000130-0x0000000000000137]
[ 5301.595877] Mem abort info:
[ 5301.595881]   ESR = 0x0000000096000006
[ 5301.595885]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 5301.595889]   SET = 0, FnV = 0
[ 5301.595893]   EA = 0, S1PTW = 0
[ 5301.595896]   FSC = 0x06: level 2 translation fault
[ 5301.595900] Data abort info:
[ 5301.595903]   ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
[ 5301.595907]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 5301.595911]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 5301.595915] [dfff800000000026] address between user and kernel address ranges
[ 5301.595971] Internal error: Oops: 0000000096000006 [#1] SMP
…
[ 5301.596076] CPU: 2 PID: 102769 Comm:
syz-executor.3 Kdump: loaded Tainted:
 G        W         -------  ---  6.10.0-0.rc2.20240608gitdc772f8237f9.29.fc41.aarch64+debug #1
[ 5301.596080] Hardware name: VMware, Inc. VMware20,1/VBSA,
 BIOS VMW201.00V.21805430.BA64.2305221830 05/22/2023
[ 5301.596082] pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 5301.596085] pc : strnlen+0x40/0x88
[ 5301.596114] lr : trace_event_get_offsets_qdisc_reset+0x6c/0x2b0
[ 5301.596124] sp : ffff8000beef6b40
[ 5301.596126] x29: ffff8000beef6b40 x28: dfff800000000000 x27: 0000000000000001
[ 5301.596131] x26: 6de1800082c62bd0 x25: 1ffff000110aa9e0 x24: ffff800088554f00
[ 5301.596136] x23: ffff800088554ec0 x22: 0000000000000130 x21: 0000000000000140
[ 5301.596140] x20: dfff800000000000 x19: ffff8000beef6c60 x18: ffff7000115106d8
[ 5301.596143] x17: ffff800121bad000 x16: ffff800080020000 x15: 0000000000000006
[ 5301.596147] x14: 0000000000000002 x13: ffff0001f3ed8d14 x12: ffff700017ddeda5
[ 5301.596151] x11: 1ffff00017ddeda4 x10: ffff700017ddeda4 x9 : ffff800082cc5eec
[ 5301.596155] x8 : 0000000000000004 x7 : 00000000f1f1f1f1 x6 : 00000000f2f2f200
[ 5301.596158] x5 : 00000000f3f3f3f3 x4 : ffff700017dded80 x3 : 00000000f204f1f1
[ 5301.596162] x2 : 0000000000000026 x1 : 0000000000000000 x0 : 0000000000000130
[ 5301.596166] Call trace:
[ 5301.596175]  strnlen+0x40/0x88
[ 5301.596179]  trace_event_get_offsets_qdisc_reset+0x6c/0x2b0
[ 5301.596182]  perf_trace_qdisc_reset+0xb0/0x538
[ 5301.596184]  __traceiter_qdisc_reset+0x68/0xc0
[ 5301.596188]  qdisc_reset+0x43c/0x5e8
[ 5301.596190]  netif_set_real_num_tx_queues+0x288/0x770
[ 5301.596194]  veth_init_queues+0xfc/0x130 [veth]
[ 5301.596198]  veth_newlink+0x45c/0x850 [veth]
[ 5301.596202]  rtnl_newlink_create+0x2c8/0x798
[ 5301.596205]  __rtnl_newlink+0x92c/0xb60
[ 5301.596208]  rtnl_newlink+0xd8/0x130
[ 5301.596211]  rtnetlink_rcv_msg+0x2e0/0x890
[ 5301.596214]  netlink_rcv_skb+0x1c4/0x380
[ 5301.596225]  rtnetlink_rcv+0x20/0x38
[ 5301.596227]  netlink_unicast+0x3c8/0x640
[ 5301.596231]  netlink_sendmsg+0x658/0xa60
[ 5301.596234]  __sock_sendmsg+0xd0/0x180
[ 5301.596243]  __sys_sendto+0x1c0/0x280
[ 5301.596246]  __arm64_sys_sendto+0xc8/0x150
[ 5301.596249]  invoke_syscall+0xdc/0x268
[ 5301.596256]  el0_svc_common.constprop.0+0x16c/0x240
[ 5301.596259]  do_el0_svc+0x48/0x68
[ 5301.596261]  el0_svc+0x50/0x188
[ 5301.596265]  el0t_64_sync_handler+0x120/0x130
[ 5301.596268]  el0t_64_sync+0x194/0x198
[ 5301.596272] Code: eb15001f 54000120 d343fc02 12000801 (38f46842) 
[ 5301.596285] SMP: stopping secondary CPUs
[ 5301.597053] Starting crashdump kernel...
[ 5301.597057] Bye!

Yeoreum and I don't know if the patch we wrote will fix the underlying cause,
but we think that priority is to prevent kernel panic happening.
So, we're sending this patch.

Signed-off-by: Yunseong Kim <yskelg@gmail.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
 include/trace/events/qdisc.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/trace/events/qdisc.h b/include/trace/events/qdisc.h
index f1b5e816e7e5..170b51fbe47a 100644
--- a/include/trace/events/qdisc.h
+++ b/include/trace/events/qdisc.h
@@ -81,7 +81,7 @@ TRACE_EVENT(qdisc_reset,
 	TP_ARGS(q),
 
 	TP_STRUCT__entry(
-		__string(	dev,		qdisc_dev(q)->name	)
+		__string(dev, qdisc_dev(q) ? qdisc_dev(q)->name : "noop_queue")
 		__string(	kind,		q->ops->id		)
 		__field(	u32,		parent			)
 		__field(	u32,		handle			)
-- 
2.45.2

Re: [PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()

[Jakub Kicinski]

On Sat, 22 Jun 2024 01:25:54 +0900 yskelg@gmail.com wrote:
> Subject: [PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()

the Fixes tag goes before your signoff, rather than as title.
try

  git log --grep=Fixes
-- 
pw-bot: cr

Re: [PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()

[Yunseong Kim]

Hi Jakub,

On 6/22/24 9:05 오전, Jakub Kicinski wrote:
> On Sat, 22 Jun 2024 01:25:54 +0900 yskelg@gmail.com wrote:
>> Subject: [PATCH net v2] net/sched: Fixes: 51270d573a8d NULL ptr deref in perf_trace_qdisc_reset()
> 
> the Fixes tag goes before your signoff, rather than as title.
> try
> 
>   git log --grep=Fixes

Oh, I'm sorry. I completely misunderstood. Thank you for kindly explaining!

I'll take your advice and send the next version of the patch!

Warm Regards,
Yunseong Kim