CVE-2024-36972: af_unix: Update unix_sk(sk)->oob_skb under sk_receive_queue lock.
First published: Mon Jun 10 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: af_unix: Update unix_sk(sk)->oob_skb under sk_receive_queue lock. Billy Jheng Bing-Jhong reported a race between __unix_gc() and queue_oob(). __unix_gc() tries to garbage-collect close()d inflight sockets, and then if the socket has MSG_OOB in unix_sk(sk)->oob_skb, GC will drop the reference and set NULL to it locklessly. However, the peer socket still can send MSG_OOB message and queue_oob() can update unix_sk(sk)->oob_skb concurrently, leading NULL pointer dereference. [0] To fix the issue, let's update unix_sk(sk)->oob_skb under the sk_receive_queue's lock and take it everywhere we touch oob_skb. Note that we defer kfree_skb() in manage_oob() to silence lockdep false-positive (See [1]). [0]: BUG: kernel NULL pointer dereference, address: 0000000000000008 PF: supervisor write access in kernel mode PF: error_code(0x0002) - not-present page PGD 8000000009f5e067 P4D 8000000009f5e067 PUD 9f5d067 PMD 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc5-00191-gd091e579b864 #110 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: events delayed_fput RIP: 0010:skb_dequeue (./include/linux/skbuff.h:2386 ./include/linux/skbuff.h:2402 net/core/skbuff.c:3847) Code: 39 e3 74 3e 8b 43 10 48 89 ef 83 e8 01 89 43 10 49 8b 44 24 08 49 c7 44 24 08 00 00 00 00 49 8b 14 24 49 c7 04 24 00 00 00 00 <48> 89 42 08 48 89 10 e8 e7 c5 42 00 4c 89 e0 5b 5d 41 5c c3 cc cc RSP: 0018:ffffc900001bfd48 EFLAGS: 00000002 RAX: 0000000000000000 RBX: ffff8880088f5ae8 RCX: 00000000361289f9 RDX: 0000000000000000 RSI: 0000000000000206 RDI: ffff8880088f5b00 RBP: ffff8880088f5b00 R08: 0000000000080000 R09: 0000000000000001 R10: 0000000000000003 R11: 0000000000000001 R12: ffff8880056b6a00 R13: ffff8880088f5280 R14: 0000000000000001 R15: ffff8880088f5a80 FS: 0000000000000000(0000) GS:ffff88807dd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 0000000006314000 CR4: 00000000007506f0 PKRU: 55555554 Call Trace: <TASK> unix_release_sock (net/unix/af_unix.c:654) unix_release (net/unix/af_unix.c:1050) __sock_release (net/socket.c:660) sock_close (net/socket.c:1423) __fput (fs/file_table.c:423) delayed_fput (fs/file_table.c:444 (discriminator 3)) process_one_work (kernel/workqueue.c:3259) worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416) kthread (kernel/kthread.c:388) ret_from_fork (arch/x86/kernel/process.c:153) ret_from_fork_asm (arch/x86/entry/entry_64.S:257) </TASK> Modules linked in: CR2: 0000000000000008
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Google Android | ||
| debian/linux | 5.10.223-1 5.10.226-1 6.1.115-1 6.1.119-1 6.11.10-1 6.12.5-1 |
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Reference Links
- https://git.kernel.org/stable/c/4708f49add84a57ce0ccc7bf9a6269845c631cc3
- https://git.kernel.org/stable/c/4bf6964451c3cb411fbaa1ae8b214b3d97a59bf1
- https://git.kernel.org/stable/c/518a994aa0b87d96f1bc6678a7035df5d1fcd7a1
- https://git.kernel.org/stable/c/9841991a446c87f90f66f4b9fee6fe934c1336a2
- https://git.kernel.org/stable/c/d59ae9314b97e01c76a4171472441e55721ba636
- https://android.googlesource.com/kernel/common/+/3169d3641a8f6e1c2c61c328d171665c5ec65780
- https://android.googlesource.com/kernel/common/+/5c86c33a36e96a7ef91645d41dd3bf2ece19a8ca
- https://android.googlesource.com/kernel/common/+/685a016cdeac2b7f1d968c6b56e698547976e10d
- https://android.googlesource.com/kernel/common/+/30d168eb06cd8bd51d5cbf9c374b8bc6b667d7f6
- https://android.googlesource.com/kernel/common/+/0e9ee9221f28d842f9d764cf4ce1e600a62470a7
- https://android.googlesource.com/kernel/common/+/de6fb073c606c19695893b874c005741fa4c0f06
- https://source.android.com/docs/security/bulletin/2024-09-01 (Advisory)
- https://launchpad.net/bugs/cve/CVE-2024-36972
- https://git.kernel.org/linus/9841991a446c87f90f66f4b9fee6fe934c1336a2
- https://security-tracker.debian.org/tracker/CVE-2024-36972
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-36972
- https://nvd.nist.gov/vuln/detail/CVE-2024-36972
- https://ubuntu.com/security/CVE-2024-36972
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