Linux: Double Free
CVE-2022-50248 is a high-severity double 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 0e1e311fd929c6a8dcfddcb4748c47b07e39821f, ae966649f665bc3868b935157dd4a3c31810dcc0, d8e32f1bf1a9183a6aad560c6688500222d24299 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 0.16% 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 0e1e311fd929c6a8dcfddcb4748c47b07e39821f or ae966649f665bc3868b935157dd4a3c31810dcc0 or d8e32f1bf1a9183a6aad560c6688500222d24299 or 8fabe41fba907e4fd826acbbdb42e09c681c515e, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.229 or 5.10.163 or 5.15.86 or 6.0.16, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, 0e1e311fd929c6a8dcfddcb4748c47b07e39821f; 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, ae966649f665bc3868b935157dd4a3c31810dcc0; 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, d8e32f1bf1a9183a6aad560c6688500222d24299; 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, 8fabe41fba907e4fd826acbbdb42e09c681c515e; 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, 3a2ecd1ec14075117ccb3e85f0fed224578ec228; 08f7d8b69aaf137db8ee0a2d7c9e6cd6383ae250 up to, but not including, 0473cbae2137b963bd0eaa74336131cb1d3bc6c3; 5.1 | 0e1e311fd929c6a8dcfddcb4748c47b07e39821f, ae966649f665bc3868b935157dd4a3c31810dcc0, d8e32f1bf1a9183a6aad560c6688500222d24299, 8fabe41fba907e4fd826acbbdb42e09c681c515e, 3a2ecd1ec14075117ccb3e85f0fed224578ec228, 0473cbae2137b963bd0eaa74336131cb1d3bc6c3 |
| Linux | Linux Kernel | 5.1 up to, but not including, 5.4.229; 5.5 up to, but not including, 5.10.163; 5.11 up to, but not including, 5.15.86; 5.16 up to, but not including, 6.0.16; 6.1 up to, but not including, 6.1.2 | 5.4.229, 5.10.163, 5.15.86, 6.0.16, 6.1.2 |
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 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: wifi: iwlwifi: mvm: fix double free on tx path. We see kernel crashes and lockups and KASAN errors related to ax210 firmware crashes. One of the KASAN dumps pointed at the tx path, and it appears there is indeed a way to double-free an skb. If iwl_mvm_tx_skb_sta returns non-zero, then the 'skb' sent into the method will be freed. But, in case where we build TSO skb buffer, the skb may also be freed in error case. So, return 0 in that particular error case and do cleanup manually. BUG: KASAN: use-after-free in __list_del_entry_valid+0x12/0x90 iwlwifi 0000:06:00.0: 0x00000000 | tsf hi Read of size 8 at addr ffff88813cfa4ba0 by task btserver/9650 CPU: 4 PID: 9650 Comm: btserver Tainted: G W 5.19.8+ #5 iwlwifi 0000:06:00.0: 0x00000000 | time gp1 Hardware name: Default string Default string/SKYBAY, BIOS 5.12 02/19/2019 Call Trace: <TASK> dump_stack_lvl+0x55/0x6d print_report.cold.12+0xf2/0x684 iwlwifi 0000:06:00.0: 0x1D0915A8 | time gp2 ? __list_del_entry_valid+0x12/0x90 kasan_report+0x8b/0x180 iwlwifi 0000:06:00.0: 0x00000001 | uCode revision type ? __list_del_entry_valid+0x12/0x90 __list_del_entry_valid+0x12/0x90 iwlwifi 0000:06:00.0: 0x00000048 | uCode version major tcp_update_skb_after_send+0x5d/0x170 __tcp_transmit_skb+0xb61/0x15c0 iwlwifi 0000:06:00.0: 0xDAA05125 | uCode version minor ? __tcp_select_window+0x490/0x490 iwlwifi 0000:06:00.0: 0x00000420 | hw version ? trace_kmalloc_node+0x29/0xd0 ? __kmalloc_node_track_caller+0x12a/0x260 ? memset+0x1f/0x40 ? __build_skb_around+0x125/0x150 ? __alloc_skb+0x1d4/0x220 ? skb_zerocopy_clone+0x55/0x230 iwlwifi 0000:06:00.0: 0x00489002 | board version ? kmalloc_reserve+0x80/0x80 ? rcu_read_lock_bh_held+0x60/0xb0 tcp_write_xmit+0x3f1/0x24d0 iwlwifi 0000:06:00.0: 0x034E001C | hcmd ? __check_object_size+0x180/0x350 iwlwifi 0000:06:00.0: 0x24020000 | isr0 tcp_sendmsg_locked+0x8a9/0x1520 iwlwifi 0000:06:00.0: 0x01400000 | isr1 ? tcp_sendpage+0x50/0x50 iwlwifi 0000:06:00.0: 0x48F0000A | isr2 ? lock_release+0xb9/0x400 ? tcp_sendmsg+0x14/0x40 iwlwifi 0000:06:00.0: 0x00C3080C | isr3 ? lock_downgrade+0x390/0x390 ? do_raw_spin_lock+0x114/0x1d0 iwlwifi 0000:06:00.0: 0x00200000 | isr4 ? rwlock_bug.part.2+0x50/0x50 iwlwifi 0000:06:00.0: 0x034A001C | last cmd Id ? rwlock_bug.part.2+0x50/0x50 ? lockdep_hardirqs_on_prepare+0xe/0x200 iwlwifi 0000:06:00.0: 0x0000C2F0 | wait_event ? __local_bh_enable_ip+0x87/0xe0 ? inet_send_prepare+0x220/0x220 iwlwifi 0000:06:00.0: 0x000000C4 | l2p_control tcp_sendmsg+0x22/0x40 sock_sendmsg+0x5f/0x70 iwlwifi 0000:06:00.0: 0x00010034 | l2p_duration __sys_sendto+0x19d/0x250 iwlwifi 0000:06:00.0: 0x00000007 | l2p_mhvalid ? __ia32_sys_getpeername+0x40/0x40 iwlwifi 0000:06:00.0: 0x00000000 | l2p_addr_match ? rcu_read_lock_held_common+0x12/0x50 ? rcu_read_lock_sched_held+0x5a/0xd0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? rcu_read_lock_sched_held+0x5a/0xd0 ? rcu_read_lock_sched_held+0x5a/0xd0 ? lock_release+0xb9/0x400 ? lock_downgrade+0x390/0x390 ? ktime_get+0x64/0x130 ? ktime_get+0x8d/0x130 ? rcu_read_lock_held_common+0x12/0x50 ? rcu_read_lock_sched_held+0x5a/0xd0 ? rcu_read_lock_held_common+0x12/0x50 ? rcu_read_lock_sched_held+0x5a/0xd0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? rcu_read_lock_bh_held+0xb0/0xb0 __x64_sys_sendto+0x6f/0x80 do_syscall_64+0x34/0xb0 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f1d126e4531 Code: 00 00 00 00 0f 1f 44 00 00 f3 0f 1e fa 48 8d 05 35 80 0c 00 41 89 ca 8b 00 85 c0 75 1c 45 31 c9 45 31 c0 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 67 c3 66 0f 1f 44 00 00 55 48 83 ec 20 48 89 RSP: 002b:00007ffe21a679d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 000000000000ffdc RCX: 00007f1d126e4531 RDX: 0000000000010000 RSI: 000000000374acf0 RDI: 0000000000000014 RBP: 00007ffe21a67ac0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R ---truncated---
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/0473cbae2137b963bd0eaa74336131cb1d3bc6c3
- git.kernel.org/stable/c/0e1e311fd929c6a8dcfddcb4748c47b07e39821f
- git.kernel.org/stable/c/3a2ecd1ec14075117ccb3e85f0fed224578ec228
- git.kernel.org/stable/c/8fabe41fba907e4fd826acbbdb42e09c681c515e
- git.kernel.org/stable/c/ae966649f665bc3868b935157dd4a3c31810dcc0
- git.kernel.org/stable/c/d8e32f1bf1a9183a6aad560c6688500222d24299
Recent Double Free vulnerabilities
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- 7.8 High severity
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