Linux: Use After Free
CVE-2022-49505 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 a8e03bcad52dc9afabf650fdbad84f739cec9efa, f81270125b50532624400063281e6611ecd61ddf, 6abfaca8711803d0d7cc8c0fac1070a88509d463 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 a8e03bcad52dc9afabf650fdbad84f739cec9efa or f81270125b50532624400063281e6611ecd61ddf or 6abfaca8711803d0d7cc8c0fac1070a88509d463 or fbf9c4c714d3cdeb98b6a18e4d057f931cad1d81, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.5 or 4.9.318 or 4.14.283 or 4.19.247, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | ff169909eac9e00bf1aa0af739ba6ddfb1b1d135 up to, but not including, a8e03bcad52dc9afabf650fdbad84f739cec9efa; 47244ac0b65bd74cc70007d8e1bac68bd2baad19 up to, but not including, f81270125b50532624400063281e6611ecd61ddf; c45cea83e13699bdfd47842e04d09dd43af4c371 up to, but not including, 6abfaca8711803d0d7cc8c0fac1070a88509d463; 307d2e6cebfca9d92f86c8e2c8e3dd4a8be46ba6 up to, but not including, fbf9c4c714d3cdeb98b6a18e4d057f931cad1d81; 73a0d12114b4bc1a9def79a623264754b9df698e up to, but not including, 2a1b5110c95e4d49c8c3906270dfcde680a5a7be; 8a9c61c3ef187d8891225f9b932390670a43a0d3 up to, but not including, 1632be63862f183cd5cf1cc094e698e6ec005dfd; 3e3b5dfcd16a3e254aab61bd1e8c417dd4503102 up to, but not including, 4a68938f43b7c2663e4c90bb9bbe29ac8b9a42a0; 3e3b5dfcd16a3e254aab61bd1e8c417dd4503102 up to, but not including, 4f5d71930f41be78557f9714393179025baacd65; and 10 more ranges | a8e03bcad52dc9afabf650fdbad84f739cec9efa, f81270125b50532624400063281e6611ecd61ddf, 6abfaca8711803d0d7cc8c0fac1070a88509d463, fbf9c4c714d3cdeb98b6a18e4d057f931cad1d81, 2a1b5110c95e4d49c8c3906270dfcde680a5a7be, 1632be63862f183cd5cf1cc094e698e6ec005dfd |
| Linux | Linux Kernel | 4.4.293 up to, but not including, 4.5; 4.9.291 up to, but not including, 4.9.318; 4.14.256 up to, but not including, 4.14.283; 4.19.218 up to, but not including, 4.19.247; 5.4.162 up to, but not including, 5.4.198; 5.10.82 up to, but not including, 5.10.121; 5.15.5 up to, but not including, 5.15.46; 5.16 up to, but not including, 5.17.14; and 1 more ranges | 4.5, 4.9.318, 4.14.283, 4.19.247, 5.4.198, 5.10.121 |
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: NULL out the dev->rfkill to prevent UAF Commit 3e3b5dfcd16a ("NFC: reorder the logic in nfc_{un,}register_device") assumes the device_is_registered() in function nfc_dev_up() will help to check when the rfkill is unregistered. However, this check only take effect when device_del(&dev->dev) is done in nfc_unregister_device(). Hence, the rfkill object is still possible be dereferenced. The crash trace in latest kernel (5.18-rc2): [ 68.760105] ================================================================== [ 68.760330] BUG: KASAN: use-after-free in __lock_acquire+0x3ec1/0x6750 [ 68.760756] Read of size 8 at addr ffff888009c93018 by task fuzz/313 [ 68.760756] [ 68.760756] CPU: 0 PID: 313 Comm: fuzz Not tainted 5.18.0-rc2 #4 [ 68.760756] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 68.760756] Call Trace: [ 68.760756] <TASK> [ 68.760756] dump_stack_lvl+0x57/0x7d [ 68.760756] print_report.cold+0x5e/0x5db [ 68.760756] ? __lock_acquire+0x3ec1/0x6750 [ 68.760756] kasan_report+0xbe/0x1c0 [ 68.760756] ? __lock_acquire+0x3ec1/0x6750 [ 68.760756] __lock_acquire+0x3ec1/0x6750 [ 68.760756] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 68.760756] ? register_lock_class+0x18d0/0x18d0 [ 68.760756] lock_acquire+0x1ac/0x4f0 [ 68.760756] ? rfkill_blocked+0xe/0x60 [ 68.760756] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 68.760756] ? mutex_lock_io_nested+0x12c0/0x12c0 [ 68.760756] ? nla_get_range_signed+0x540/0x540 [ 68.760756] ? _raw_spin_lock_irqsave+0x4e/0x50 [ 68.760756] _raw_spin_lock_irqsave+0x39/0x50 [ 68.760756] ? rfkill_blocked+0xe/0x60 [ 68.760756] rfkill_blocked+0xe/0x60 [ 68.760756] nfc_dev_up+0x84/0x260 [ 68.760756] nfc_genl_dev_up+0x90/0xe0 [ 68.760756] genl_family_rcv_msg_doit+0x1f4/0x2f0 [ 68.760756] ? genl_family_rcv_msg_attrs_parse.constprop.0+0x230/0x230 [ 68.760756] ? security_capable+0x51/0x90 [ 68.760756] genl_rcv_msg+0x280/0x500 [ 68.760756] ? genl_get_cmd+0x3c0/0x3c0 [ 68.760756] ? lock_acquire+0x1ac/0x4f0 [ 68.760756] ? nfc_genl_dev_down+0xe0/0xe0 [ 68.760756] ? lockdep_hardirqs_on_prepare+0x410/0x410 [ 68.760756] netlink_rcv_skb+0x11b/0x340 [ 68.760756] ? genl_get_cmd+0x3c0/0x3c0 [ 68.760756] ? netlink_ack+0x9c0/0x9c0 [ 68.760756] ? netlink_deliver_tap+0x136/0xb00 [ 68.760756] genl_rcv+0x1f/0x30 [ 68.760756] netlink_unicast+0x430/0x710 [ 68.760756] ? memset+0x20/0x40 [ 68.760756] ? netlink_attachskb+0x740/0x740 [ 68.760756] ? __build_skb_around+0x1f4/0x2a0 [ 68.760756] netlink_sendmsg+0x75d/0xc00 [ 68.760756] ? netlink_unicast+0x710/0x710 [ 68.760756] ? netlink_unicast+0x710/0x710 [ 68.760756] sock_sendmsg+0xdf/0x110 [ 68.760756] __sys_sendto+0x19e/0x270 [ 68.760756] ? __ia32_sys_getpeername+0xa0/0xa0 [ 68.760756] ? fd_install+0x178/0x4c0 [ 68.760756] ? fd_install+0x195/0x4c0 [ 68.760756] ? kernel_fpu_begin_mask+0x1c0/0x1c0 [ 68.760756] __x64_sys_sendto+0xd8/0x1b0 [ 68.760756] ? lockdep_hardirqs_on+0xbf/0x130 [ 68.760756] ? syscall_enter_from_user_mode+0x1d/0x50 [ 68.760756] do_syscall_64+0x3b/0x90 [ 68.760756] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 68.760756] RIP: 0033:0x7f67fb50e6b3 ... [ 68.760756] RSP: 002b:00007f67fa91fe90 EFLAGS: 00000293 ORIG_RAX: 000000000000002c [ 68.760756] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f67fb50e6b3 [ 68.760756] RDX: 000000000000001c RSI: 0000559354603090 RDI: 0000000000000003 [ 68.760756] RBP: 00007f67fa91ff00 R08: 00007f67fa91fedc R09: 000000000000000c [ 68.760756] R10: 0000000000000000 R11: 0000000000000293 R12: 00007ffe824d496e [ 68.760756] R13: 00007ffe824d496f R14: 00007f67fa120000 R15: 0000000000000003 [ 68.760756] </TASK> [ 68.760756] [ 68.760756] Allocated by task 279: [ 68.760756] kasan_save_stack+0x1e/0x40 [ ---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/1632be63862f183cd5cf1cc094e698e6ec005dfd
- git.kernel.org/stable/c/1b0e81416a24d6e9b8c2341e22e8bf48f8b8bfc9
- git.kernel.org/stable/c/2a1b5110c95e4d49c8c3906270dfcde680a5a7be
- git.kernel.org/stable/c/4a68938f43b7c2663e4c90bb9bbe29ac8b9a42a0
- git.kernel.org/stable/c/4f5d71930f41be78557f9714393179025baacd65
- git.kernel.org/stable/c/6abfaca8711803d0d7cc8c0fac1070a88509d463
- git.kernel.org/stable/c/a8e03bcad52dc9afabf650fdbad84f739cec9efa
- git.kernel.org/stable/c/f81270125b50532624400063281e6611ecd61ddf
- git.kernel.org/stable/c/fbf9c4c714d3cdeb98b6a18e4d057f931cad1d81
Recent Use After Free vulnerabilities
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