CVE-2022-50214: In the Linux kernel, the following vulnerability has been resolved:  coresight: Clear the connection field properly  coresight devices track their connections (output connections) and hold a reference to the fwnode. When a device goes away, we walk through the devices on the coresight bus and make sure that the references are dropped. This happens both ways:  a) For all output connections from the device, drop the reference to     the target device via coresight_release_platform_data()  b) Iterate over all the devices on the coresight bus and drop the    reference to fwnode if *this* device is the target of the output    connection, via coresight_remove_conns()->coresight_remove_match().  However, the coresight_remove_match() doesn't clear the fwnode field, after dropping the reference, this causes use-after-free and additional refcount drops on the fwnode.  e.g., if we have two devices, A and B, with a connection, A -> B. If we remove B first, B would clear the reference on B, from A via coresight_remove_match(). But when A is removed, it still has a connection with fwnode still pointing to B. Thus it tries to  drops the reference in coresight_release_platform_data(), raising the bells like :  [   91.990153] ------------[ cut here ]------------ [   91.990163] refcount_t: addition on 0; use-after-free. [   91.990212] WARNING: CPU: 0 PID: 461 at lib/refcount.c:25 refcount_warn_saturate+0xa0/0x144 [   91.990260] Modules linked in: coresight_funnel coresight_replicator coresight_etm4x(-)  crct10dif_ce coresight ip_tables x_tables ipv6 [last unloaded: coresight_cpu_debug] [   91.990398] CPU: 0 PID: 461 Comm: rmmod Tainted: G        W       T 5.19.0-rc2+ #53 [   91.990418] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb  1 2019 [   91.990434] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [   91.990454] pc : refcount_warn_saturate+0xa0/0x144 [   91.990476] lr : refcount_warn_saturate+0xa0/0x144 [   91.990496] sp : ffff80000c843640 [   91.990509] x29: ffff80000c843640 x28: ffff800009957c28 x27: ffff80000c8439a8 [   91.990560] x26: ffff00097eff1990 x25: ffff8000092b6ad8 x24: ffff00097eff19a8 [   91.990610] x23: ffff80000c8439a8 x22: 0000000000000000 x21: ffff80000c8439c2 [   91.990659] x20: 0000000000000000 x19: ffff00097eff1a10 x18: ffff80000ab99c40 [   91.990708] x17: 0000000000000000 x16: 0000000000000000 x15: ffff80000abf6fa0 [   91.990756] x14: 000000000000001d x13: 0a2e656572662d72 x12: 657466612d657375 [   91.990805] x11: 203b30206e6f206e x10: 6f69746964646120 x9 : ffff8000081aba28 [   91.990854] x8 : 206e6f206e6f6974 x7 : 69646461203a745f x6 : 746e756f63666572 [   91.990903] x5 : ffff00097648ec58 x4 : 0000000000000000 x3 : 0000000000000027 [   91.990952] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff00080260ba00 [   91.991000] Call trace: [   91.991012]  refcount_warn_saturate+0xa0/0x144 [   91.991034]  kobject_get+0xac/0xb0 [   91.991055]  of_node_get+0x2c/0x40 [   91.991076]  of_fwnode_get+0x40/0x60 [   91.991094]  fwnode_handle_get+0x3c/0x60 [   91.991116]  fwnode_get_nth_parent+0xf4/0x110 [   91.991137]  fwnode_full_name_string+0x48/0xc0 [   91.991158]  device_node_string+0x41c/0x530 [   91.991178]  pointer+0x320/0x3ec [   91.991198]  vsnprintf+0x23c/0x750 [   91.991217]  vprintk_store+0x104/0x4b0 [   91.991238]  vprintk_emit+0x8c/0x360 [   91.991257]  vprintk_default+0x44/0x50 [   91.991276]  vprintk+0xcc/0xf0 [   91.991295]  _printk+0x68/0x90 [   91.991315]  of_node_release+0x13c/0x14c [   91.991334]  kobject_put+0x98/0x114 [   91.991354]  of_node_put+0x24/0x34 [   91.991372]  of_fwnode_put+0x40/0x5c [   91.991390]  fwnode_handle_put+0x38/0x50 [   91.991411]  coresight_release_platform_data+0x74/0xb0 [coresight] [   91.991472]  coresight_unregister+0x64/0xcc [coresight] [   91.991525]  etm4_remove_dev+0x64/0x78 [coresight_etm4x] [   91.991563]  etm4_remove_amba+0x1c/0x2c [coresight_etm4x] [   91.991598]  amba_remove+0x3c/0x19c ---truncated---