Linux: Use After Free
CVE-2022-48878 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 e84ec6e25df9bb0968599e92eacedaf3a0a5b587, 908d1742b6e694e84ead5c62e4b7c1bfbb8b46a3, ea3ebda47dd56f6e1c62f2e0e1b6e1b0a973e447 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 0.24% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to e84ec6e25df9bb0968599e92eacedaf3a0a5b587 or 908d1742b6e694e84ead5c62e4b7c1bfbb8b46a3 or ea3ebda47dd56f6e1c62f2e0e1b6e1b0a973e447 or 272970be3dabd24cbe50e393ffee8f04aec3b9a8, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.165 or 5.15.90 or 6.1.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7e7bbddd029b644f00f0ffbfbc485ed71977d0d5 up to, but not including, e84ec6e25df9bb0968599e92eacedaf3a0a5b587; 7e7bbddd029b644f00f0ffbfbc485ed71977d0d5 up to, but not including, 908d1742b6e694e84ead5c62e4b7c1bfbb8b46a3; 7e7bbddd029b644f00f0ffbfbc485ed71977d0d5 up to, but not including, ea3ebda47dd56f6e1c62f2e0e1b6e1b0a973e447; 7e7bbddd029b644f00f0ffbfbc485ed71977d0d5 up to, but not including, 272970be3dabd24cbe50e393ffee8f04aec3b9a8; 5.8 | e84ec6e25df9bb0968599e92eacedaf3a0a5b587, 908d1742b6e694e84ead5c62e4b7c1bfbb8b46a3, ea3ebda47dd56f6e1c62f2e0e1b6e1b0a973e447, 272970be3dabd24cbe50e393ffee8f04aec3b9a8 |
| Linux | Linux Kernel | 5.8 up to, but not including, 5.10.165; 5.11 up to, but not including, 5.15.90; 5.16 up to, but not including, 6.1.8 | 5.10.165, 5.15.90, 6.1.8 |
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 system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_qca: Fix driver shutdown on closed serdev The driver shutdown callback (which sends EDL_SOC_RESET to the device over serdev) should not be invoked when HCI device is not open (e.g. if hci_dev_open_sync() failed), because the serdev and its TTY are not open either. Also skip this step if device is powered off (qca_power_shutdown()). The shutdown callback causes use-after-free during system reboot with Qualcomm Atheros Bluetooth: Unable to handle kernel paging request at virtual address 0072662f67726fd7 ... CPU: 6 PID: 1 Comm: systemd-shutdow Tainted: G W 6.1.0-rt5-00325-g8a5f56bcfcca #8 Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT) Call trace: tty_driver_flush_buffer+0x4/0x30 serdev_device_write_flush+0x24/0x34 qca_serdev_shutdown+0x80/0x130 [hci_uart] device_shutdown+0x15c/0x260 kernel_restart+0x48/0xac KASAN report: BUG: KASAN: use-after-free in tty_driver_flush_buffer+0x1c/0x50 Read of size 8 at addr ffff16270c2e0018 by task systemd-shutdow/1 CPU: 7 PID: 1 Comm: systemd-shutdow Not tainted 6.1.0-next-20221220-00014-gb85aaf97fb01-dirty #28 Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT) Call trace: dump_backtrace.part.0+0xdc/0xf0 show_stack+0x18/0x30 dump_stack_lvl+0x68/0x84 print_report+0x188/0x488 kasan_report+0xa4/0xf0 __asan_load8+0x80/0xac tty_driver_flush_buffer+0x1c/0x50 ttyport_write_flush+0x34/0x44 serdev_device_write_flush+0x48/0x60 qca_serdev_shutdown+0x124/0x274 device_shutdown+0x1e8/0x350 kernel_restart+0x48/0xb0 __do_sys_reboot+0x244/0x2d0 __arm64_sys_reboot+0x54/0x70 invoke_syscall+0x60/0x190 el0_svc_common.constprop.0+0x7c/0x160 do_el0_svc+0x44/0xf0 el0_svc+0x2c/0x6c el0t_64_sync_handler+0xbc/0x140 el0t_64_sync+0x190/0x194
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.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use After Free vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
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