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Dan Williams 49f2dab77a cxl/port: Hold port reference until decoder release 
[ Upstream commit 74be98774d ]

KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in
cxl_decoder_release() where it goes to reference its parent, a cxl_port,
to free its id back to port->decoder_ida.

 BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core]
 Read of size 8 at addr ffff888119270908 by task kworker/35:2/379

 CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G           OE     5.17.0-rc2+ #198
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 Workqueue: events kobject_delayed_cleanup
 Call Trace:
  <TASK>
  dump_stack_lvl+0x59/0x73
  print_address_description.constprop.0+0x1f/0x150
  ? to_cxl_port+0x18/0x90 [cxl_core]
  kasan_report.cold+0x83/0xdf
  ? to_cxl_port+0x18/0x90 [cxl_core]
  to_cxl_port+0x18/0x90 [cxl_core]
  cxl_decoder_release+0x2a/0x60 [cxl_core]
  device_release+0x5f/0x100
  kobject_cleanup+0x80/0x1c0

The device core only guarantees parent lifetime until all children are
unregistered. If a child needs a parent to complete its ->release()
callback that child needs to hold a reference to extend the lifetime of
the parent.

Fixes: 40ba17afdf ("cxl/acpi: Introduce cxl_decoder objects")
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Tested-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164505751190.4175768.13324905271463416712.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-04-08 13:58:07 +02:00
..
core cxl/port: Hold port reference until decoder release 2022-04-08 13:58:07 +02:00
Kconfig cxl/acpi: Convert CFMWS parsing to ACPI sub-table helpers 2021-11-15 11:02:59 -08:00
Makefile cxl: Move cxl_core to new directory 2021-08-06 08:22:53 -07:00
acpi.c ACPI: NUMA: Add a node and memblk for each CFMWS not in SRAT 2021-11-15 11:03:00 -08:00
cxl.h cxl/core: Remove cxld_const_init in cxl_decoder_alloc() 2022-01-04 17:29:31 -08:00
cxlmem.h cxl/memdev: Remove unused cxlmd field 2021-11-15 11:02:59 -08:00
pci.c cxl/memdev: Change cxl_mem to a more descriptive name 2021-11-15 11:02:58 -08:00
pci.h cxl/pci: Convert register block identifiers to an enum 2021-10-29 11:53:51 -07:00
pmem.c cxl/pmem: Fix module reload vs workqueue state 2021-11-15 11:03:00 -08:00