CVE-2024-42271 net/iucv: fix use after free in iucv_sock_close()

2024-08-1708:54:26

Linux

www.cve.org

linux kernel

iucv_sock_close

use after free

iucv_sever_path

atomic compare

severing the path

iucv_callback_connrej

iucv_tasklet_fn

bh_lock_sock

tasklet context

process context

iucv tasklet

worker.

EPSS

Percentile

5.0%

JSON

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

net/iucv: fix use after free in iucv_sock_close()

iucv_sever_path() is called from process context and from bh context.
iucv->path is used as indicator whether somebody else is taking care of
severing the path (or it is already removed / never existed).
This needs to be done with atomic compare and swap, otherwise there is a
small window where iucv_sock_close() will try to work with a path that has
already been severed and freed by iucv_callback_connrej() called by
iucv_tasklet_fn().

Example:
[452744.123844] Call Trace:
[452744.123845] ([<0000001e87f03880>] 0x1e87f03880)
[452744.123966] [<00000000d593001e>] iucv_path_sever+0x96/0x138
[452744.124330] [<000003ff801ddbca>] iucv_sever_path+0xc2/0xd0 [af_iucv]
[452744.124336] [<000003ff801e01b6>] iucv_sock_close+0xa6/0x310 [af_iucv]
[452744.124341] [<000003ff801e08cc>] iucv_sock_release+0x3c/0xd0 [af_iucv]
[452744.124345] [<00000000d574794e>] __sock_release+0x5e/0xe8
[452744.124815] [<00000000d5747a0c>] sock_close+0x34/0x48
[452744.124820] [<00000000d5421642>] __fput+0xba/0x268
[452744.124826] [<00000000d51b382c>] task_work_run+0xbc/0xf0
[452744.124832] [<00000000d5145710>] do_notify_resume+0x88/0x90
[452744.124841] [<00000000d5978096>] system_call+0xe2/0x2c8
[452744.125319] Last Breaking-Event-Address:
[452744.125321] [<00000000d5930018>] iucv_path_sever+0x90/0x138
[452744.125324]
[452744.125325] Kernel panic - not syncing: Fatal exception in interrupt

Note that bh_lock_sock() is not serializing the tasklet context against
process context, because the check for sock_owned_by_user() and
corresponding handling is missing.

Ideas for a future clean-up patch:
A) Correct usage of bh_lock_sock() in tasklet context, as described in
Re-enqueue, if needed. This may require adding return values to the
tasklet functions and thus changes to all users of iucv.

B) Change iucv tasklet into worker and use only lock_sock() in af_iucv.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/iucv/af_iucv.c"
    ],
    "versions": [
      {
        "version": "7d316b945352",
        "lessThan": "84f40b46787e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "37652fbef980",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "c65f72eec60a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "ac758e1f663f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "8b424c9e4411",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "01437282fd39",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "69620522c48c",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "7d316b945352",
        "lessThan": "f558120cd709",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/iucv/af_iucv.c"
    ],
    "versions": [
      {
        "version": "3.4",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "3.4",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.320",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.282",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.224",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.165",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.104",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.45",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10.4",
        "lessThanOrEqual": "6.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.11",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]