[PATCH 5.8 48/70] net: protect tcf_block_unbind with block lock

Greg Kroah-Hartman
2020-10-31T11:42:05Z

From: Leon Romanovsky <leonro@nvidia.com>

[ Upstream commit d6535dca28859d8d9ef80894eb287b2ac35a32e8 ]

The tcf_block_unbind() expects that the caller will take block->cb_lock
before calling it, however the code took RTNL lock and dropped cb_lock
instead. This causes to the following kernel panic.

WARNING: CPU: 1 PID: 13524 at net/sched/cls_api.c:1488 tcf_block_unbind+0x2db/0x420
Modules linked in: mlx5_ib mlx5_core mlxfw ptp pps_core act_mirred act_tunnel_key cls_flower vxlan ip6_udp_tunnel udp_tunnel dummy sch_ingress openvswitch nsh xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 br_netfilter rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad ib_ipoib rdma_cm iw_cm ib_cm ib_uverbs ib_core overlay [last unloaded: mlxfw]
CPU: 1 PID: 13524 Comm: test-ecmp-add-v Tainted: G W 5.9.0+ #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:tcf_block_unbind+0x2db/0x420
Code: ff 48 83 c4 40 5b 5d 41 5c 41 5d 41 5e 41 5f c3 49 8d bc 24 30 01 00 00 be ff ff ff ff e8 7d 7f 70 00 85 c0 0f 85 7b fd ff ff <0f> 0b e9 74 fd ff ff 48 c7 c7 dc 6a 24 84 e8 02 ec fe fe e9 55 fd
RSP: 0018:ffff888117d17968 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88812f713c00 RCX: 1ffffffff0848d5b
RDX: 0000000000000001 RSI: ffff88814fbc8130 RDI: ffff888107f2b878
RBP: 1ffff11022fa2f3f R08: 0000000000000000 R09: ffffffff84115a87
R10: fffffbfff0822b50 R11: ffff888107f2b898 R12: ffff88814fbc8000
R13: ffff88812f713c10 R14: ffff888117d17a38 R15: ffff88814fbc80c0
FS: 00007f6593d36740(0000) GS:ffff8882a4f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005607a00758f8 CR3: 0000000131aea006 CR4: 0000000000170ea0
Call Trace:
tc_block_indr_cleanup+0x3e0/0x5a0
? tcf_block_unbind+0x420/0x420
? __mutex_unlock_slowpath+0xe7/0x610
flow_indr_dev_unregister+0x5e2/0x930
? mlx5e_restore_tunnel+0xdf0/0xdf0 [mlx5_core]
? mlx5e_restore_tunnel+0xdf0/0xdf0 [mlx5_core]
? flow_indr_block_cb_alloc+0x3c0/0x3c0
? mlx5_db_free+0x37c/0x4b0 [mlx5_core]
mlx5e_cleanup_rep_tx+0x8b/0xc0 [mlx5_core]
mlx5e_detach_netdev+0xe5/0x120 [mlx5_core]
mlx5e_vport_rep_unload+0x155/0x260 [mlx5_core]
esw_offloads_disable+0x227/0x2b0 [mlx5_core]
mlx5_eswitch_disable_locked.cold+0x38e/0x699 [mlx5_core]
mlx5_eswitch_disable+0x94/0xf0 [mlx5_core]
mlx5_device_disable_sriov+0x183/0x1f0 [mlx5_core]
mlx5_core_sriov_configure+0xfd/0x230 [mlx5_core]
sriov_numvfs_store+0x261/0x2f0
? sriov_drivers_autoprobe_store+0x110/0x110
? sysfs_file_ops+0x170/0x170
? sysfs_file_ops+0x117/0x170
? sysfs_file_ops+0x170/0x170
kernfs_fop_write+0x1ff/0x3f0
? rcu_read_lock_any_held+0x6e/0x90
vfs_write+0x1f3/0x620
ksys_write+0xf9/0x1d0
? __x64_sys_read+0xb0/0xb0
? lockdep_hardirqs_on_prepare+0x273/0x3f0
? syscall_enter_from_user_mode+0x1d/0x50
do_syscall_64+0x2d/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9

<...>

---[ end trace bfdd028ada702879 ]---

Fixes: 0fdcf78d5973 ("net: use flow_indr_dev_setup_offload()")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20201026123327.1141066-1-leon@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/cls_api.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -650,12 +650,12 @@ static void tc_block_indr_cleanup(struct
block_cb->indr.binder_type,
&block->flow_block, tcf_block_shared(block),
&extack);
+ rtnl_lock();
down_write(&block->cb_lock);
list_del(&block_cb->driver_list);
list_move(&block_cb->list, &bo.cb_list);
- up_write(&block->cb_lock);
- rtnl_lock();
tcf_block_unbind(block, &bo);
+ up_write(&block->cb_lock);
rtnl_unlock();
}