CyberSecBulletin
CVE-2022-49842NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-49842 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 41fad4f712e081acdfde8b59847f9f66eaf407a0, 90bbdf30a51e42378cb23a312005a022794b8e1e, a3365e62239dc064019a244bde5686ac18527c22 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 41fad4f712e081acdfde8b59847f9f66eaf407a0 or 90bbdf30a51e42378cb23a312005a022794b8e1e or a3365e62239dc064019a244bde5686ac18527c22 or 2ec3f558db343b045a7c7419cdbaec266b8ac1a7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.9.334 or 4.14.300 or 4.19.267 or 5.4.225, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxfb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 41fad4f712e081acdfde8b59847f9f66eaf407a0; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 90bbdf30a51e42378cb23a312005a022794b8e1e; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, a3365e62239dc064019a244bde5686ac18527c22; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 2ec3f558db343b045a7c7419cdbaec266b8ac1a7; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 8d21554ec7680e9585fb852d933203c3db60dad1; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 34eee4189bcebbd5f6a2ff25ef0cb893ad33d51e; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, c5674bd073c0fd9f620ca550c5ff08d0d429bdd9; fb257897bf20c5f0e1df584bb5b874e811651263 up to, but not including, 6ec27c53886c8963729885bcf2dd996eba2767a7; and 1 more ranges41fad4f712e081acdfde8b59847f9f66eaf407a0, 90bbdf30a51e42378cb23a312005a022794b8e1e, a3365e62239dc064019a244bde5686ac18527c22, 2ec3f558db343b045a7c7419cdbaec266b8ac1a7, 8d21554ec7680e9585fb852d933203c3db60dad1, 34eee4189bcebbd5f6a2ff25ef0cb893ad33d51e
LinuxLinux Kernel3.0 up to, but not including, 4.9.334; 4.10 up to, but not including, 4.14.300; 4.15 up to, but not including, 4.19.267; 4.20 up to, but not including, 5.4.225; 5.5 up to, but not including, 5.10.156; 5.11 up to, but not including, 5.15.80; 5.16 up to, but not including, 6.0.10; 6.14.9.334, 4.14.300, 4.19.267, 5.4.225, 5.10.156, 5.15.80

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)

Official description

In the Linux kernel, the following vulnerability has been resolved: ASoC: core: Fix use-after-free in snd_soc_exit() KASAN reports a use-after-free: BUG: KASAN: use-after-free in device_del+0xb5b/0xc60 Read of size 8 at addr ffff888008655050 by task rmmod/387 CPU: 2 PID: 387 Comm: rmmod Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Call Trace: <TASK> dump_stack_lvl+0x79/0x9a print_report+0x17f/0x47b kasan_report+0xbb/0xf0 device_del+0xb5b/0xc60 platform_device_del.part.0+0x24/0x200 platform_device_unregister+0x2e/0x40 snd_soc_exit+0xa/0x22 [snd_soc_core] __do_sys_delete_module.constprop.0+0x34f/0x5b0 do_syscall_64+0x3a/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd ... </TASK> It's bacause in snd_soc_init(), snd_soc_util_init() is possble to fail, but its ret is ignored, which makes soc_dummy_dev unregistered twice. snd_soc_init() snd_soc_util_init() platform_device_register_simple(soc_dummy_dev) platform_driver_register() # fail platform_device_unregister(soc_dummy_dev) platform_driver_register() # success ... snd_soc_exit() snd_soc_util_exit() # soc_dummy_dev will be unregistered for second time To fix it, handle error and stop snd_soc_init() when util_init() fail. Also clean debugfs when util_init() or driver_register() fail.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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