Linux: Use After Free
CVE-2022-49465 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 24ba80efaf6e772f6132465fad08e20fb4767da7, 047ea38d41d90d748bca812a43339632f52ba715, 0cfc8a0fb07cde61915e4a77c4794c47de3114a4 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.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 24ba80efaf6e772f6132465fad08e20fb4767da7 or 047ea38d41d90d748bca812a43339632f52ba715 or 0cfc8a0fb07cde61915e4a77c4794c47de3114a4 or 935fa666534d7b7185e8c6b0191cd06281be4290, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.248 or 5.15.198 or 5.17.14 or 5.18.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2a0f61e6ecd08d260054bde4b096ff207ce5350f up to, but not including, 24ba80efaf6e772f6132465fad08e20fb4767da7; 2a0f61e6ecd08d260054bde4b096ff207ce5350f up to, but not including, 047ea38d41d90d748bca812a43339632f52ba715; 2a0f61e6ecd08d260054bde4b096ff207ce5350f up to, but not including, 0cfc8a0fb07cde61915e4a77c4794c47de3114a4; 2a0f61e6ecd08d260054bde4b096ff207ce5350f up to, but not including, 935fa666534d7b7185e8c6b0191cd06281be4290; 2a0f61e6ecd08d260054bde4b096ff207ce5350f up to, but not including, 5a011f889b4832aa80c2a872a5aade5c48d2756f; 3.11 | 24ba80efaf6e772f6132465fad08e20fb4767da7, 047ea38d41d90d748bca812a43339632f52ba715, 0cfc8a0fb07cde61915e4a77c4794c47de3114a4, 935fa666534d7b7185e8c6b0191cd06281be4290, 5a011f889b4832aa80c2a872a5aade5c48d2756f |
| Linux | Linux Kernel | before 5.10.248; 5.11 up to, but not including, 5.15.198; 5.16 up to, but not including, 5.17.14; 5.18 up to, but not including, 5.18.3 | 5.10.248, 5.15.198, 5.17.14, 5.18.3 |
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: blk-throttle: Set BIO_THROTTLED when bio has been throttled 1.In current process, all bio will set the BIO_THROTTLED flag after __blk_throtl_bio(). 2.If bio needs to be throttled, it will start the timer and stop submit bio directly. Bio will submit in blk_throtl_dispatch_work_fn() when the timer expires.But in the current process, if bio is throttled. The BIO_THROTTLED will be set to bio after timer start. If the bio has been completed, it may cause use-after-free blow. BUG: KASAN: use-after-free in blk_throtl_bio+0x12f0/0x2c70 Read of size 2 at addr ffff88801b8902d4 by task fio/26380 dump_stack+0x9b/0xce print_address_description.constprop.6+0x3e/0x60 kasan_report.cold.9+0x22/0x3a blk_throtl_bio+0x12f0/0x2c70 submit_bio_checks+0x701/0x1550 submit_bio_noacct+0x83/0xc80 submit_bio+0xa7/0x330 mpage_readahead+0x380/0x500 read_pages+0x1c1/0xbf0 page_cache_ra_unbounded+0x471/0x6f0 do_page_cache_ra+0xda/0x110 ondemand_readahead+0x442/0xae0 page_cache_async_ra+0x210/0x300 generic_file_buffered_read+0x4d9/0x2130 generic_file_read_iter+0x315/0x490 blkdev_read_iter+0x113/0x1b0 aio_read+0x2ad/0x450 io_submit_one+0xc8e/0x1d60 __se_sys_io_submit+0x125/0x350 do_syscall_64+0x2d/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Allocated by task 26380: kasan_save_stack+0x19/0x40 __kasan_kmalloc.constprop.2+0xc1/0xd0 kmem_cache_alloc+0x146/0x440 mempool_alloc+0x125/0x2f0 bio_alloc_bioset+0x353/0x590 mpage_alloc+0x3b/0x240 do_mpage_readpage+0xddf/0x1ef0 mpage_readahead+0x264/0x500 read_pages+0x1c1/0xbf0 page_cache_ra_unbounded+0x471/0x6f0 do_page_cache_ra+0xda/0x110 ondemand_readahead+0x442/0xae0 page_cache_async_ra+0x210/0x300 generic_file_buffered_read+0x4d9/0x2130 generic_file_read_iter+0x315/0x490 blkdev_read_iter+0x113/0x1b0 aio_read+0x2ad/0x450 io_submit_one+0xc8e/0x1d60 __se_sys_io_submit+0x125/0x350 do_syscall_64+0x2d/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 0: kasan_save_stack+0x19/0x40 kasan_set_track+0x1c/0x30 kasan_set_free_info+0x1b/0x30 __kasan_slab_free+0x111/0x160 kmem_cache_free+0x94/0x460 mempool_free+0xd6/0x320 bio_free+0xe0/0x130 bio_put+0xab/0xe0 bio_endio+0x3a6/0x5d0 blk_update_request+0x590/0x1370 scsi_end_request+0x7d/0x400 scsi_io_completion+0x1aa/0xe50 scsi_softirq_done+0x11b/0x240 blk_mq_complete_request+0xd4/0x120 scsi_mq_done+0xf0/0x200 virtscsi_vq_done+0xbc/0x150 vring_interrupt+0x179/0x390 __handle_irq_event_percpu+0xf7/0x490 handle_irq_event_percpu+0x7b/0x160 handle_irq_event+0xcc/0x170 handle_edge_irq+0x215/0xb20 common_interrupt+0x60/0x120 asm_common_interrupt+0x1e/0x40 Fix this by move BIO_THROTTLED set into the queue_lock.
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/047ea38d41d90d748bca812a43339632f52ba715
- git.kernel.org/stable/c/0cfc8a0fb07cde61915e4a77c4794c47de3114a4
- git.kernel.org/stable/c/24ba80efaf6e772f6132465fad08e20fb4767da7
- git.kernel.org/stable/c/5a011f889b4832aa80c2a872a5aade5c48d2756f
- git.kernel.org/stable/c/935fa666534d7b7185e8c6b0191cd06281be4290
Recent Use After Free vulnerabilities
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