Highly exploitable, CVE-2024-47711 poses a critical security risk that could lead to severe breaches.
Status: Analyzed
Last updated: 🕑 24 Oct 2024, 14:03 UTC
Originally published on: 🕛 21 Oct 2024, 12:15 UTC
Time between publication and last update: 3 days
CVSS Release: version 3
nvd@nist.gov
Primary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVE-2024-47711: In the Linux kernel, the following vulnerability has been resolved: af_unix: Don't return OOB skb in manage_oob(). syzbot reported use-after-free in unix_stream_recv_urg(). [0] The scenario is 1. send(MSG_OOB) 2. recv(MSG_OOB) -> The consumed OOB remains in recv queue 3. send(MSG_OOB) 4. recv() -> manage_oob() returns the next skb of the consumed OOB -> This is also OOB, but unix_sk(sk)->oob_skb is not cleared 5. recv(MSG_OOB) -> unix_sk(sk)->oob_skb is used but already freed The recent commit 8594d9b85c07 ("af_unix: Don't call skb_get() for OOB skb.") uncovered the issue. If the OOB skb is consumed and the next skb is peeked in manage_oob(), we still need to check if the skb is OOB. Let's do so by falling back to the following checks in manage_oob() and add the test case in selftest. Note that we need to add a similar check for SIOCATMARK. [0]: BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959 Read of size 4 at addr ffff8880326abcc4 by task syz-executor178/5235 CPU: 0 UID: 0 PID: 5235 Comm: syz-executor178 Not tainted 6.11.0-rc5-syzkaller-00742-gfbdaffe41adc #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959 unix_stream_recv_urg+0x1df/0x320 net/unix/af_unix.c:2640 unix_stream_read_generic+0x2456/0x2520 net/unix/af_unix.c:2778 unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996 sock_recvmsg_nosec net/socket.c:1046 [inline] sock_recvmsg+0x22f/0x280 net/socket.c:1068 ____sys_recvmsg+0x1db/0x470 net/socket.c:2816 ___sys_recvmsg net/socket.c:2858 [inline] __sys_recvmsg+0x2f0/0x3e0 net/socket.c:2888 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5360d6b4e9 Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff29b3a458 EFLAGS: 00000246 ORIG_RAX: 000000000000002f RAX: ffffffffffffffda RBX: 00007fff29b3a638 RCX: 00007f5360d6b4e9 RDX: 0000000000002001 RSI: 0000000020000640 RDI: 0000000000000003 RBP: 00007f5360dde610 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fff29b3a628 R14: 0000000000000001 R15: 0000000000000001 </TASK> Allocated by task 5235: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:312 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook mm/slub.c:3988 [inline] slab_alloc_node mm/slub.c:4037 [inline] kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4080 __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667 alloc_skb include/linux/skbuff.h:1320 [inline] alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6528 sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815 sock_alloc_send_skb include/net/sock.h:1778 [inline] queue_oob+0x108/0x680 net/unix/af_unix.c:2198 unix_stream_sendmsg+0xd24/0xf80 net/unix/af_unix.c:2351 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597 ___sys_sendmsg net/socket.c:2651 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 5235: kasan_save_stack mm/kasan/common.c:47 ---truncated---
The exploitability of CVE-2024-47711 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2024-47711 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2024-47711, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2024-47711, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.043% (probability of exploit)
EPSS Percentile: 11.87%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 88.13% of others.
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