CyberSecBulletin
CVE-2022-49667NVD status: Analyzed

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2022-49667 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 a853b7a3a9fd1d74a4ccdd9cd73512b7dace2f1e, b90ac60303063a43e17dd4aec159067599d255e6, f162f7c348fa2a5555bafdb5cc890b89b221e69c 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 0.29% 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 a853b7a3a9fd1d74a4ccdd9cd73512b7dace2f1e or b90ac60303063a43e17dd4aec159067599d255e6 or f162f7c348fa2a5555bafdb5cc890b89b221e69c or 893825289ba840afd86bfffcb6f7f363c73efff8, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.9.322 or 4.14.287 or 4.19.251 or 5.4.204, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, a853b7a3a9fd1d74a4ccdd9cd73512b7dace2f1e; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, b90ac60303063a43e17dd4aec159067599d255e6; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, f162f7c348fa2a5555bafdb5cc890b89b221e69c; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, 893825289ba840afd86bfffcb6f7f363c73efff8; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, 63b2fe509f69b90168a75e04e14573dccf7984e6; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, ef0af7d08d26c5333ff4944a559279464edf6f15; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, 2765749def4765c5052a4c66445cf4c96fcccdbc; 0622cab0341cac6b30da177b0faa39fae0680e71 up to, but not including, 050133e1aa2cb49bb17be847d48a4431598ef562; and 1 more rangesa853b7a3a9fd1d74a4ccdd9cd73512b7dace2f1e, b90ac60303063a43e17dd4aec159067599d255e6, f162f7c348fa2a5555bafdb5cc890b89b221e69c, 893825289ba840afd86bfffcb6f7f363c73efff8, 63b2fe509f69b90168a75e04e14573dccf7984e6, ef0af7d08d26c5333ff4944a559279464edf6f15
LinuxLinux Kernel4.7 up to, but not including, 4.9.322; 4.10 up to, but not including, 4.14.287; 4.15 up to, but not including, 4.19.251; 4.20 up to, but not including, 5.4.204; 5.5 up to, but not including, 5.10.129; 5.11 up to, but not including, 5.15.53; 5.16 up to, but not including, 5.18.10; 5.194.9.322, 4.14.287, 4.19.251, 5.4.204, 5.10.129, 5.15.53

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 CISA (ADP).

Official description

In the Linux kernel, the following vulnerability has been resolved: net: bonding: fix use-after-free after 802.3ad slave unbind commit 0622cab0341c ("bonding: fix 802.3ad aggregator reselection"), resolve case, when there is several aggregation groups in the same bond. bond_3ad_unbind_slave will invalidate (clear) aggregator when __agg_active_ports return zero. So, ad_clear_agg can be executed even, when num_of_ports!=0. Than bond_3ad_unbind_slave can be executed again for, previously cleared aggregator. NOTE: at this time bond_3ad_unbind_slave will not update slave ports list, because lag_ports==NULL. So, here we got slave ports, pointing to freed aggregator memory. Fix with checking actual number of ports in group (as was before commit 0622cab0341c ("bonding: fix 802.3ad aggregator reselection") ), before ad_clear_agg(). The KASAN logs are as follows: [ 767.617392] ================================================================== [ 767.630776] BUG: KASAN: use-after-free in bond_3ad_state_machine_handler+0x13dc/0x1470 [ 767.638764] Read of size 2 at addr ffff00011ba9d430 by task kworker/u8:7/767 [ 767.647361] CPU: 3 PID: 767 Comm: kworker/u8:7 Tainted: G O 5.15.11 #15 [ 767.655329] Hardware name: DNI AmazonGo1 A7040 board (DT) [ 767.660760] Workqueue: lacp_1 bond_3ad_state_machine_handler [ 767.666468] Call trace: [ 767.668930] dump_backtrace+0x0/0x2d0 [ 767.672625] show_stack+0x24/0x30 [ 767.675965] dump_stack_lvl+0x68/0x84 [ 767.679659] print_address_description.constprop.0+0x74/0x2b8 [ 767.685451] kasan_report+0x1f0/0x260 [ 767.689148] __asan_load2+0x94/0xd0 [ 767.692667] bond_3ad_state_machine_handler+0x13dc/0x1470

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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