CVE-2023-52849 cxl/mem: Fix shutdown order

2024-05-2115:31:45

Linux

github.com

linux kernel

vulnerability

fix shutdown order

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.6%

JSON

In the Linux kernel, the following vulnerability has been resolved:

cxl/mem: Fix shutdown order

Ira reports that removing cxl_mock_mem causes a crash with the following
trace:

BUG: kernel NULL pointer dereference, address: 0000000000000044
[…]
RIP: 0010:cxl_region_decode_reset+0x7f/0x180 [cxl_core]
[…]
Call Trace:
<TASK>
cxl_region_detach+0xe8/0x210 [cxl_core]
cxl_decoder_kill_region+0x27/0x40 [cxl_core]
cxld_unregister+0x29/0x40 [cxl_core]
devres_release_all+0xb8/0x110
device_unbind_cleanup+0xe/0x70
device_release_driver_internal+0x1d2/0x210
bus_remove_device+0xd7/0x150
device_del+0x155/0x3e0
device_unregister+0x13/0x60
devm_release_action+0x4d/0x90
? __pfx_unregister_port+0x10/0x10 [cxl_core]
delete_endpoint+0x121/0x130 [cxl_core]
devres_release_all+0xb8/0x110
device_unbind_cleanup+0xe/0x70
device_release_driver_internal+0x1d2/0x210
bus_remove_device+0xd7/0x150
device_del+0x155/0x3e0
? lock_release+0x142/0x290
cdev_device_del+0x15/0x50
cxl_memdev_unregister+0x54/0x70 [cxl_core]

This crash is due to the clearing out the cxl_memdev’s driver context
(@cxlds) before the subsystem is done with it. This is ultimately due to
the region(s), that this memdev is a member, being torn down and expecting
to be able to de-reference @cxlds, like here:

static int cxl_region_decode_reset(struct cxl_region *cxlr, int count)
…
if (cxlds->rcd)
goto endpoint_reset;
…

Fix it by keeping the driver context valid until memdev-device
unregistration, and subsequently the entire stack of related
dependencies, unwinds.

CNA Affected

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "9cc238c7a526",
        "lessThan": "20bd0198bebd",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9cc238c7a526",
        "lessThan": "7c7371b41a14",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9cc238c7a526",
        "lessThan": "cad22a757029",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9cc238c7a526",
        "lessThan": "0ca074f7d788",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "9cc238c7a526",
        "lessThan": "88d3917f82ed",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/cxl/core/memdev.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.15"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.15",
        "versionType": "custom"
      },
      {
        "status": "unaffected",
        "version": "5.15.139",
        "versionType": "custom",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.63",
        "versionType": "custom",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.5.12",
        "versionType": "custom",
        "lessThanOrEqual": "6.5.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.2",
        "versionType": "custom",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.7",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/cxl/core/memdev.c"
    ],
    "defaultStatus": "affected"
  }
]