CyberSecBulletin
CVE-2022-49290NVD status: Modified

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2022-49290 is a high-severity double 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 615716af8644813355e014314a0bc1e961250f5a, c1d9c3628ef0a0ca197595d0f9e01cd3b5dda186, 273ebddc5fda2967492cb0b6cdd7d81cfb821b76 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 0.26% 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 615716af8644813355e014314a0bc1e961250f5a or c1d9c3628ef0a0ca197595d0f9e01cd3b5dda186 or 273ebddc5fda2967492cb0b6cdd7d81cfb821b76 or 3bbd0000d012f92aec423b224784fbf0f7bf40f8, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.5 or 4.9.309 or 4.14.274 or 4.19.237, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux3212d6248faf0efce6b7a718e198feecce0eea05 up to, but not including, 615716af8644813355e014314a0bc1e961250f5a; 86e7d4cd2ed5f4b0188afce8199faffcf1ae7c7e up to, but not including, c1d9c3628ef0a0ca197595d0f9e01cd3b5dda186; 37bccfa89559a70c044b5ccde3c916a91388e14a up to, but not including, 273ebddc5fda2967492cb0b6cdd7d81cfb821b76; 3f15e3e62c80e180282f0cbc5559264e11c328b7 up to, but not including, 3bbd0000d012f92aec423b224784fbf0f7bf40f8; 6a01afcf8468d3ca2bd8bbb27503f60dcf643b20 up to, but not including, 5d3ff9542a40ce034416bca03864709540a36016; 6a01afcf8468d3ca2bd8bbb27503f60dcf643b20 up to, but not including, 12e407a8ef17623823fd0c066fbd7f103953d28d; 6a01afcf8468d3ca2bd8bbb27503f60dcf643b20 up to, but not including, 582d8c60c0c053684f7138875e8150d5749ffc17; 6a01afcf8468d3ca2bd8bbb27503f60dcf643b20 up to, but not including, 46bb87d40683337757a2f902fcd4244b32bb4e86; and 10 more ranges615716af8644813355e014314a0bc1e961250f5a, c1d9c3628ef0a0ca197595d0f9e01cd3b5dda186, 273ebddc5fda2967492cb0b6cdd7d81cfb821b76, 3bbd0000d012f92aec423b224784fbf0f7bf40f8, 5d3ff9542a40ce034416bca03864709540a36016, 12e407a8ef17623823fd0c066fbd7f103953d28d
LinuxLinux Kernel4.4.233 up to, but not including, 4.5; 4.9.233 up to, but not including, 4.9.309; 4.14.192 up to, but not including, 4.14.274; 4.19.137 up to, but not including, 4.19.237; 5.4.56 up to, but not including, 5.4.188; 5.7.13 up to, but not including, 5.10.109; 5.11 up to, but not including, 5.15.32; 5.16 up to, but not including, 5.16.18; and 1 more ranges4.5, 4.9.309, 4.14.274, 4.19.237, 5.4.188, 5.10.109

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: mac80211: fix potential double free on mesh join While commit 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") fixed a memory leak on mesh leave / teardown it introduced a potential memory corruption caused by a double free when rejoining the mesh: ieee80211_leave_mesh() -> kfree(sdata->u.mesh.ie); ... ieee80211_join_mesh() -> copy_mesh_setup() -> old_ie = ifmsh->ie; -> kfree(old_ie); This double free / kernel panics can be reproduced by using wpa_supplicant with an encrypted mesh (if set up without encryption via "iw" then ifmsh->ie is always NULL, which avoids this issue). And then calling: $ iw dev mesh0 mesh leave $ iw dev mesh0 mesh join my-mesh Note that typically these commands are not used / working when using wpa_supplicant. And it seems that wpa_supplicant or wpa_cli are going through a NETDEV_DOWN/NETDEV_UP cycle between a mesh leave and mesh join where the NETDEV_UP resets the mesh.ie to NULL via a memcpy of default_mesh_setup in cfg80211_netdev_notifier_call, which then avoids the memory corruption, too. The issue was first observed in an application which was not using wpa_supplicant but "Senf" instead, which implements its own calls to nl80211. Fixing the issue by removing the kfree()'ing of the mesh IE in the mesh join function and leaving it solely up to the mesh leave to free the mesh IE.

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

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

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 Double Free vulnerabilities

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