Linux: Use After Free
CVE-2022-49179 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 c4f5a678add58a8a0e7ee5e038496b376ea6d205, 7507ead1e9d42957c2340f2c4a0e9d00034e3366, 8f34dea99cd7761156a146a5258a67d045d862f7 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 0.28% 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 c4f5a678add58a8a0e7ee5e038496b376ea6d205 or 7507ead1e9d42957c2340f2c4a0e9d00034e3366 or 8f34dea99cd7761156a146a5258a67d045d862f7 or 87fdfe8589d43e471dffb4c60f75eeb6f37afc4c, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.189 or 5.10.110 or 5.15.33 or 5.16.19, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, c4f5a678add58a8a0e7ee5e038496b376ea6d205; 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, 7507ead1e9d42957c2340f2c4a0e9d00034e3366; 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, 8f34dea99cd7761156a146a5258a67d045d862f7; 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, 87fdfe8589d43e471dffb4c60f75eeb6f37afc4c; 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, c01fced8d38fbccc82787065229578006f28e020; 0d52af590552473666da5b6111e7182d6cd23f92 up to, but not including, 8410f70977734f21b8ed45c37e925d311dfda2e7; 4.16 | c4f5a678add58a8a0e7ee5e038496b376ea6d205, 7507ead1e9d42957c2340f2c4a0e9d00034e3366, 8f34dea99cd7761156a146a5258a67d045d862f7, 87fdfe8589d43e471dffb4c60f75eeb6f37afc4c, c01fced8d38fbccc82787065229578006f28e020, 8410f70977734f21b8ed45c37e925d311dfda2e7 |
| Linux | Linux Kernel | before 5.4.189; 5.5 up to, but not including, 5.10.110; 5.11 up to, but not including, 5.15.33; 5.16 up to, but not including, 5.16.19; 5.17 up to, but not including, 5.17.2 | 5.4.189, 5.10.110, 5.15.33, 5.16.19, 5.17.2 |
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 CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: block, bfq: don't move oom_bfqq Our test report a UAF: [ 2073.019181] ================================================================== [ 2073.019188] BUG: KASAN: use-after-free in __bfq_put_async_bfqq+0xa0/0x168 [ 2073.019191] Write of size 8 at addr ffff8000ccf64128 by task rmmod/72584 [ 2073.019192] [ 2073.019196] CPU: 0 PID: 72584 Comm: rmmod Kdump: loaded Not tainted 4.19.90-yk #5 [ 2073.019198] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 [ 2073.019200] Call trace: [ 2073.019203] dump_backtrace+0x0/0x310 [ 2073.019206] show_stack+0x28/0x38 [ 2073.019210] dump_stack+0xec/0x15c [ 2073.019216] print_address_description+0x68/0x2d0 [ 2073.019220] kasan_report+0x238/0x2f0 [ 2073.019224] __asan_store8+0x88/0xb0 [ 2073.019229] __bfq_put_async_bfqq+0xa0/0x168 [ 2073.019233] bfq_put_async_queues+0xbc/0x208 [ 2073.019236] bfq_pd_offline+0x178/0x238 [ 2073.019240] blkcg_deactivate_policy+0x1f0/0x420 [ 2073.019244] bfq_exit_queue+0x128/0x178 [ 2073.019249] blk_mq_exit_sched+0x12c/0x160 [ 2073.019252] elevator_exit+0xc8/0xd0 [ 2073.019256] blk_exit_queue+0x50/0x88 [ 2073.019259] blk_cleanup_queue+0x228/0x3d8 [ 2073.019267] null_del_dev+0xfc/0x1e0 [null_blk] [ 2073.019274] null_exit+0x90/0x114 [null_blk] [ 2073.019278] __arm64_sys_delete_module+0x358/0x5a0 [ 2073.019282] el0_svc_common+0xc8/0x320 [ 2073.019287] el0_svc_handler+0xf8/0x160 [ 2073.019290] el0_svc+0x10/0x218 [ 2073.019291] [ 2073.019294] Allocated by task 14163: [ 2073.019301] kasan_kmalloc+0xe0/0x190 [ 2073.019305] kmem_cache_alloc_node_trace+0x1cc/0x418 [ 2073.019308] bfq_pd_alloc+0x54/0x118 [ 2073.019313] blkcg_activate_policy+0x250/0x460 [ 2073.019317] bfq_create_group_hierarchy+0x38/0x110 [ 2073.019321] bfq_init_queue+0x6d0/0x948 [ 2073.019325] blk_mq_init_sched+0x1d8/0x390 [ 2073.019330] elevator_switch_mq+0x88/0x170 [ 2073.019334] elevator_switch+0x140/0x270 [ 2073.019338] elv_iosched_store+0x1a4/0x2a0 [ 2073.019342] queue_attr_store+0x90/0xe0 [ 2073.019348] sysfs_kf_write+0xa8/0xe8 [ 2073.019351] kernfs_fop_write+0x1f8/0x378 [ 2073.019359] __vfs_write+0xe0/0x360 [ 2073.019363] vfs_write+0xf0/0x270 [ 2073.019367] ksys_write+0xdc/0x1b8 [ 2073.019371] __arm64_sys_write+0x50/0x60 [ 2073.019375] el0_svc_common+0xc8/0x320 [ 2073.019380] el0_svc_handler+0xf8/0x160 [ 2073.019383] el0_svc+0x10/0x218 [ 2073.019385] [ 2073.019387] Freed by task 72584: [ 2073.019391] __kasan_slab_free+0x120/0x228 [ 2073.019394] kasan_slab_free+0x10/0x18 [ 2073.019397] kfree+0x94/0x368 [ 2073.019400] bfqg_put+0x64/0xb0 [ 2073.019404] bfqg_and_blkg_put+0x90/0xb0 [ 2073.019408] bfq_put_queue+0x220/0x228 [ 2073.019413] __bfq_put_async_bfqq+0x98/0x168 [ 2073.019416] bfq_put_async_queues+0xbc/0x208 [ 2073.019420] bfq_pd_offline+0x178/0x238 [ 2073.019424] blkcg_deactivate_policy+0x1f0/0x420 [ 2073.019429] bfq_exit_queue+0x128/0x178 [ 2073.019433] blk_mq_exit_sched+0x12c/0x160 [ 2073.019437] elevator_exit+0xc8/0xd0 [ 2073.019440] blk_exit_queue+0x50/0x88 [ 2073.019443] blk_cleanup_queue+0x228/0x3d8 [ 2073.019451] null_del_dev+0xfc/0x1e0 [null_blk] [ 2073.019459] null_exit+0x90/0x114 [null_blk] [ 2073.019462] __arm64_sys_delete_module+0x358/0x5a0 [ 2073.019467] el0_svc_common+0xc8/0x320 [ 2073.019471] el0_svc_handler+0xf8/0x160 [ 2073.019474] el0_svc+0x10/0x218 [ 2073.019475] [ 2073.019479] The buggy address belongs to the object at ffff8000ccf63f00 which belongs to the cache kmalloc-1024 of size 1024 [ 2073.019484] The buggy address is located 552 bytes inside of 1024-byte region [ffff8000ccf63f00, ffff8000ccf64300) [ 2073.019486] The buggy address belongs to the page: [ 2073.019492] page:ffff7e000333d800 count:1 mapcount:0 mapping:ffff8000c0003a00 index:0x0 compound_mapcount: 0 [ 2073.020123] flags: 0x7ffff0000008100(slab|head) [ 2073.020403] raw: 07ffff0000008100 ffff7e0003334c08 ffff7e00001f5a08 ffff8000c0003a00 [ 2073.020409] ra ---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/7507ead1e9d42957c2340f2c4a0e9d00034e3366
- git.kernel.org/stable/c/8410f70977734f21b8ed45c37e925d311dfda2e7
- git.kernel.org/stable/c/87fdfe8589d43e471dffb4c60f75eeb6f37afc4c
- git.kernel.org/stable/c/8f34dea99cd7761156a146a5258a67d045d862f7
- git.kernel.org/stable/c/c01fced8d38fbccc82787065229578006f28e020
- git.kernel.org/stable/c/c4f5a678add58a8a0e7ee5e038496b376ea6d205
Recent Use After Free vulnerabilities
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