Linux: Use After Free
CVE-2023-52772 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 75bcfc188abf4fae9c1d5f5dc0a03540be602eef, d179189eec426fe4801e4b91efa1889faed12700, eae0b295ce16d8c8b4114c3037993191b4bb92f0 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 0.24% 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 75bcfc188abf4fae9c1d5f5dc0a03540be602eef or d179189eec426fe4801e4b91efa1889faed12700 or eae0b295ce16d8c8b4114c3037993191b4bb92f0 or 069a3ec329ff43e7869a3d94c62cd03203016bce, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.140 or 6.1.64 or 6.5.13 or 6.6.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 876c14ad014d0e39c57cbfde53e13d17cdb6d645 up to, but not including, 75bcfc188abf4fae9c1d5f5dc0a03540be602eef; 876c14ad014d0e39c57cbfde53e13d17cdb6d645 up to, but not including, d179189eec426fe4801e4b91efa1889faed12700; 876c14ad014d0e39c57cbfde53e13d17cdb6d645 up to, but not including, eae0b295ce16d8c8b4114c3037993191b4bb92f0; 876c14ad014d0e39c57cbfde53e13d17cdb6d645 up to, but not including, 069a3ec329ff43e7869a3d94c62cd03203016bce; 876c14ad014d0e39c57cbfde53e13d17cdb6d645 up to, but not including, 4b7b492615cf3017190f55444f7016812b66611d; 5.15 | 75bcfc188abf4fae9c1d5f5dc0a03540be602eef, d179189eec426fe4801e4b91efa1889faed12700, eae0b295ce16d8c8b4114c3037993191b4bb92f0, 069a3ec329ff43e7869a3d94c62cd03203016bce, 4b7b492615cf3017190f55444f7016812b66611d |
| Linux | Linux Kernel | 5.15 up to, but not including, 5.15.140; 5.16 up to, but not including, 6.1.64; 6.2 up to, but not including, 6.5.13; 6.6 up to, but not including, 6.6.3 | 5.15.140, 6.1.64, 6.5.13, 6.6.3 |
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 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: af_unix: fix use-after-free in unix_stream_read_actor() syzbot reported the following crash [1] After releasing unix socket lock, u->oob_skb can be changed by another thread. We must temporarily increase skb refcount to make sure this other thread will not free the skb under us. [1] BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa7/0xc0 net/unix/af_unix.c:2866 Read of size 4 at addr ffff88801f3b9cc4 by task syz-executor107/5297 CPU: 1 PID: 5297 Comm: syz-executor107 Not tainted 6.6.0-syzkaller-15910-gb8e3a87a627b #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xc4/0x620 mm/kasan/report.c:475 kasan_report+0xda/0x110 mm/kasan/report.c:588 unix_stream_read_actor+0xa7/0xc0 net/unix/af_unix.c:2866 unix_stream_recv_urg net/unix/af_unix.c:2587 [inline] unix_stream_read_generic+0x19a5/0x2480 net/unix/af_unix.c:2666 unix_stream_recvmsg+0x189/0x1b0 net/unix/af_unix.c:2903 sock_recvmsg_nosec net/socket.c:1044 [inline] sock_recvmsg+0xe2/0x170 net/socket.c:1066 ____sys_recvmsg+0x21f/0x5c0 net/socket.c:2803 ___sys_recvmsg+0x115/0x1a0 net/socket.c:2845 __sys_recvmsg+0x114/0x1e0 net/socket.c:2875 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7fc67492c559 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc6748ab228 EFLAGS: 00000246 ORIG_RAX: 000000000000002f RAX: ffffffffffffffda RBX: 000000000000001c RCX: 00007fc67492c559 RDX: 0000000040010083 RSI: 0000000020000140 RDI: 0000000000000004 RBP: 00007fc6749b6348 R08: 00007fc6748ab6c0 R09: 00007fc6748ab6c0 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc6749b6340 R13: 00007fc6749b634c R14: 00007ffe9fac52a0 R15: 00007ffe9fac5388 </TASK> Allocated by task 5295: kasan_save_stack+0x33/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 __kasan_slab_alloc+0x81/0x90 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook mm/slab.h:763 [inline] slab_alloc_node mm/slub.c:3478 [inline] kmem_cache_alloc_node+0x180/0x3c0 mm/slub.c:3523 __alloc_skb+0x287/0x330 net/core/skbuff.c:641 alloc_skb include/linux/skbuff.h:1286 [inline] alloc_skb_with_frags+0xe4/0x710 net/core/skbuff.c:6331 sock_alloc_send_pskb+0x7e4/0x970 net/core/sock.c:2780 sock_alloc_send_skb include/net/sock.h:1884 [inline] queue_oob net/unix/af_unix.c:2147 [inline] unix_stream_sendmsg+0xb5f/0x10a0 net/unix/af_unix.c:2301 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0xd5/0x180 net/socket.c:745 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2584 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2638 __sys_sendmsg+0x117/0x1e0 net/socket.c:2667 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Freed by task 5295: kasan_save_stack+0x33/0x50 mm/kasan/common.c:45 kasan_set_track+0x25/0x30 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522 ____kasan_slab_free mm/kasan/common.c:236 [inline] ____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1800 [inline] slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826 slab_free mm/slub.c:3809 [inline] kmem_cache_free+0xf8/0x340 mm/slub.c:3831 kfree_skbmem+0xef/0x1b0 net/core/skbuff.c:1015 __kfree_skb net/core/skbuff.c:1073 [inline] consume_skb net/core/skbuff.c:1288 [inline] consume_skb+0xdf/0x170 net/core/skbuff.c:1282 queue_oob net/unix/af_unix.c:2178 [inline] u ---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: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/069a3ec329ff43e7869a3d94c62cd03203016bce
- git.kernel.org/stable/c/4b7b492615cf3017190f55444f7016812b66611d
- git.kernel.org/stable/c/75bcfc188abf4fae9c1d5f5dc0a03540be602eef
- git.kernel.org/stable/c/d179189eec426fe4801e4b91efa1889faed12700
- git.kernel.org/stable/c/eae0b295ce16d8c8b4114c3037993191b4bb92f0
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