Linux: Use After Free
CVE-2022-49059 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 7d3232214ca4ea8f7d18df264c3b254aa8089d7f, 9d243aff5f7e6b04e907c617426bbdf26e996ac8, 1a1748d0dd0f0a98535c6baeef671c8722107639 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 0.3% 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 7d3232214ca4ea8f7d18df264c3b254aa8089d7f or 9d243aff5f7e6b04e907c617426bbdf26e996ac8 or 1a1748d0dd0f0a98535c6baeef671c8722107639 or 5c63ad2b0a267a524c12c88acb1ba9c2d109a801, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.9.311 or 4.14.276 or 4.19.239 or 5.4.190, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 7d3232214ca4ea8f7d18df264c3b254aa8089d7f; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 9d243aff5f7e6b04e907c617426bbdf26e996ac8; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 1a1748d0dd0f0a98535c6baeef671c8722107639; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 5c63ad2b0a267a524c12c88acb1ba9c2d109a801; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 67677050cecbe0edfdd81cd508415e9636ba7c65; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, 9ded5ae40f4fe37fcc28f36d76bf45df20be5432; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, edd4600120641e1714e30112e69a548cfb68e067; 6a2968aaf50c7a22fced77a5e24aa636281efca8 up to, but not including, ef27324e2cb7bb24542d6cb2571740eefe6b00dc; and 1 more ranges | 7d3232214ca4ea8f7d18df264c3b254aa8089d7f, 9d243aff5f7e6b04e907c617426bbdf26e996ac8, 1a1748d0dd0f0a98535c6baeef671c8722107639, 5c63ad2b0a267a524c12c88acb1ba9c2d109a801, 67677050cecbe0edfdd81cd508415e9636ba7c65, 9ded5ae40f4fe37fcc28f36d76bf45df20be5432 |
| Linux | Linux Kernel | 3.2 up to, but not including, 4.9.311; 4.10 up to, but not including, 4.14.276; 4.15 up to, but not including, 4.19.239; 4.20 up to, but not including, 5.4.190; 5.5 up to, but not including, 5.10.112; 5.11 up to, but not including, 5.15.35; 5.16 up to, but not including, 5.17.4; 5.18 | 4.9.311, 4.14.276, 4.19.239, 5.4.190, 5.10.112, 5.15.35 |
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: nfc: nci: add flush_workqueue to prevent uaf Our detector found a concurrent use-after-free bug when detaching an NCI device. The main reason for this bug is the unexpected scheduling between the used delayed mechanism (timer and workqueue). The race can be demonstrated below: Thread-1 Thread-2 | nci_dev_up() | nci_open_device() | __nci_request(nci_reset_req) | nci_send_cmd | queue_work(cmd_work) nci_unregister_device() | nci_close_device() | ... del_timer_sync(cmd_timer)[1] | ... | Worker nci_free_device() | nci_cmd_work() kfree(ndev)[3] | mod_timer(cmd_timer)[2] In short, the cleanup routine thought that the cmd_timer has already been detached by [1] but the mod_timer can re-attach the timer [2], even it is already released [3], resulting in UAF. This UAF is easy to trigger, crash trace by POC is like below [ 66.703713] ================================================================== [ 66.703974] BUG: KASAN: use-after-free in enqueue_timer+0x448/0x490 [ 66.703974] Write of size 8 at addr ffff888009fb7058 by task kworker/u4:1/33 [ 66.703974] [ 66.703974] CPU: 1 PID: 33 Comm: kworker/u4:1 Not tainted 5.18.0-rc2 #5 [ 66.703974] Workqueue: nfc2_nci_cmd_wq nci_cmd_work [ 66.703974] Call Trace: [ 66.703974] <TASK> [ 66.703974] dump_stack_lvl+0x57/0x7d [ 66.703974] print_report.cold+0x5e/0x5db [ 66.703974] ? enqueue_timer+0x448/0x490 [ 66.703974] kasan_report+0xbe/0x1c0 [ 66.703974] ? enqueue_timer+0x448/0x490 [ 66.703974] enqueue_timer+0x448/0x490 [ 66.703974] __mod_timer+0x5e6/0xb80 [ 66.703974] ? mark_held_locks+0x9e/0xe0 [ 66.703974] ? try_to_del_timer_sync+0xf0/0xf0 [ 66.703974] ? lockdep_hardirqs_on_prepare+0x17b/0x410 [ 66.703974] ? queue_work_on+0x61/0x80 [ 66.703974] ? lockdep_hardirqs_on+0xbf/0x130 [ 66.703974] process_one_work+0x8bb/0x1510 [ 66.703974] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 66.703974] ? pwq_dec_nr_in_flight+0x230/0x230 [ 66.703974] ? rwlock_bug.part.0+0x90/0x90 [ 66.703974] ? _raw_spin_lock_irq+0x41/0x50 [ 66.703974] worker_thread+0x575/0x1190 [ 66.703974] ? process_one_work+0x1510/0x1510 [ 66.703974] kthread+0x2a0/0x340 [ 66.703974] ? kthread_complete_and_exit+0x20/0x20 [ 66.703974] ret_from_fork+0x22/0x30 [ 66.703974] </TASK> [ 66.703974] [ 66.703974] Allocated by task 267: [ 66.703974] kasan_save_stack+0x1e/0x40 [ 66.703974] __kasan_kmalloc+0x81/0xa0 [ 66.703974] nci_allocate_device+0xd3/0x390 [ 66.703974] nfcmrvl_nci_register_dev+0x183/0x2c0 [ 66.703974] nfcmrvl_nci_uart_open+0xf2/0x1dd [ 66.703974] nci_uart_tty_ioctl+0x2c3/0x4a0 [ 66.703974] tty_ioctl+0x764/0x1310 [ 66.703974] __x64_sys_ioctl+0x122/0x190 [ 66.703974] do_syscall_64+0x3b/0x90 [ 66.703974] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 66.703974] [ 66.703974] Freed by task 406: [ 66.703974] kasan_save_stack+0x1e/0x40 [ 66.703974] kasan_set_track+0x21/0x30 [ 66.703974] kasan_set_free_info+0x20/0x30 [ 66.703974] __kasan_slab_free+0x108/0x170 [ 66.703974] kfree+0xb0/0x330 [ 66.703974] nfcmrvl_nci_unregister_dev+0x90/0xd0 [ 66.703974] nci_uart_tty_close+0xdf/0x180 [ 66.703974] tty_ldisc_kill+0x73/0x110 [ 66.703974] tty_ldisc_hangup+0x281/0x5b0 [ 66.703974] __tty_hangup.part.0+0x431/0x890 [ 66.703974] tty_release+0x3a8/0xc80 [ 66.703974] __fput+0x1f0/0x8c0 [ 66.703974] task_work_run+0xc9/0x170 [ 66.703974] exit_to_user_mode_prepare+0x194/0x1a0 [ 66.703974] syscall_exit_to_user_mode+0x19/0x50 [ 66.703974] do_syscall_64+0x48/0x90 [ 66.703974] entry_SYSCALL_64_after_hwframe+0x44/0x ---truncated---
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/1a1748d0dd0f0a98535c6baeef671c8722107639
- git.kernel.org/stable/c/5c63ad2b0a267a524c12c88acb1ba9c2d109a801
- git.kernel.org/stable/c/67677050cecbe0edfdd81cd508415e9636ba7c65
- git.kernel.org/stable/c/7d3232214ca4ea8f7d18df264c3b254aa8089d7f
- git.kernel.org/stable/c/9d243aff5f7e6b04e907c617426bbdf26e996ac8
- git.kernel.org/stable/c/9ded5ae40f4fe37fcc28f36d76bf45df20be5432
- git.kernel.org/stable/c/edd4600120641e1714e30112e69a548cfb68e067
- git.kernel.org/stable/c/ef27324e2cb7bb24542d6cb2571740eefe6b00dc
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.