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Date: Sun, 2 Jul 2023 11:38:22 +0800 (GMT+08:00)
From: "Lin Ma" <linma@....edu.cn>
To: oss-security@...ts.openwall.com
Subject: CVE-2023-3439: Linux MCTP use-after-free in mctp_sendmsg
Hello,
We have found a concurrency use-after-free case in Linux kernel and assigned with CVE-2023-3439 by Red Hat Team.
Below is the details about this issue.
=*=*=*=*=*=*=*=*= Details =*=*=*=*=*=*=*=*=
bug fix patch (upstream):
https://github.com/torvalds/linux/commit/b561275d633b
bug introduce commit:
https://github.com/torvalds/linux/commit/583be982d934
required privilege:
CAP_NET_ADMIN
crash stack:
[ 86.051955] ==================================================================
[ 86.051955] BUG: KASAN: use-after-free in mctp_local_output+0x4e9/0xb7d
[ 86.051955] Read of size 1 at addr ffff888005f298c0 by task poc/295
[ 86.051955]
[ 86.051955] Call Trace:
[ 86.051955] <TASK>
[ 86.051955] dump_stack_lvl+0x33/0x42
[ 86.051955] print_report.cold.13+0xb2/0x6b3
[ 86.051955] ? preempt_schedule_irq+0x57/0x80
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] kasan_report+0xa5/0x120
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] mctp_local_output+0x4e9/0xb7d
[ 86.051955] ? mctp_dev_set_key+0x79/0x79
[ 86.051955] ? copyin+0x38/0x50
[ 86.051955] ? _copy_from_iter+0x1b6/0xf20
[ 86.051955] ? sysvec_apic_timer_interrupt+0x97/0xb0
[ 86.051955] ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[ 86.051955] ? mctp_local_output+0x1/0xb7d
[ 86.051955] mctp_sendmsg+0x64d/0xdb0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] ? __fget_light+0x2fd/0x4f0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] ? __ia32_sys_getpeername+0xa0/0xa0
[ 86.051955] ? new_sync_write+0x335/0x550
[ 86.051955] ? alloc_file+0x22f/0x500
[ 86.051955] ? __ip_do_redirect+0x820/0x1820
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? fput_many+0x15/0x120
[ 86.051955] ? ksys_write+0x155/0x1b0
[ 86.051955] ? __ia32_sys_read+0xa0/0xa0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] ? exit_to_user_mode_prepare+0x2f/0x120
[ 86.051955] ? syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955] RIP: 0033:0x7f82118a56b3
[ 86.051955] RSP: 002b:00007ffdb154b110 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
[ 86.051955] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f82118a56b3
[ 86.051955] RDX: 0000000000000010 RSI: 00007f8211cd4000 RDI: 0000000000000007
[ 86.051955] RBP: 00007ffdb154c1d0 R08: 00007ffdb154b164 R09: 000000000000000c
[ 86.051955] R10: 0000000000000000 R11: 0000000000000293 R12: 000055d779800db0
[ 86.051955] R13: 00007ffdb154c2b0 R14: 0000000000000000 R15: 0000000000000000
[ 86.051955] </TASK>
[ 86.051955]
[ 86.051955] Allocated by task 295:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] __kasan_kmalloc+0x84/0xa0
[ 86.051955] mctp_rtm_newaddr+0x242/0x610
[ 86.051955] rtnetlink_rcv_msg+0x2fd/0x8b0
[ 86.051955] netlink_rcv_skb+0x11c/0x340
[ 86.051955] netlink_unicast+0x439/0x630
[ 86.051955] netlink_sendmsg+0x752/0xc00
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] Freed by task 301:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] kasan_set_track+0x21/0x30
[ 86.051955] kasan_set_free_info+0x20/0x30
[ 86.051955] __kasan_slab_free+0x104/0x170
[ 86.051955] kfree+0x8c/0x290
[ 86.051955] mctp_dev_notify+0x161/0x2c0
[ 86.051955] raw_notifier_call_chain+0x8b/0xc0
[ 86.051955] unregister_netdevice_many+0x299/0x1180
[ 86.051955] unregister_netdevice_queue+0x210/0x2f0
[ 86.051955] unregister_netdev+0x13/0x20
[ 86.051955] mctp_serial_close+0x6d/0xa0
[ 86.051955] tty_ldisc_kill+0x31/0xa0
[ 86.051955] tty_ldisc_hangup+0x24f/0x560
[ 86.051955] __tty_hangup.part.28+0x2ce/0x6b0
[ 86.051955] tty_release+0x327/0xc70
[ 86.051955] __fput+0x1df/0x8b0
[ 86.051955] task_work_run+0xca/0x150
[ 86.051955] exit_to_user_mode_prepare+0x114/0x120
[ 86.051955] syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x46/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] The buggy address belongs to the object at ffff888005f298c0
[ 86.051955] which belongs to the cache kmalloc-8 of size 8
[ 86.051955] The buggy address is located 0 bytes inside of
[ 86.051955] 8-byte region [ffff888005f298c0, ffff888005f298c8)
[ 86.051955]
[ 86.051955] The buggy address belongs to the physical page:
[ 86.051955] flags: 0x100000000000200(slab|node=0|zone=1)
[ 86.051955] raw: 0100000000000200 dead000000000100 dead000000000122 ffff888005c42280
[ 86.051955] raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
[ 86.051955] page dumped because: kasan: bad access detected
[ 86.051955]
[ 86.051955] Memory state around the buggy address:
[ 86.051955] ffff888005f29780: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
[ 86.051955] ffff888005f29800: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc
[ 86.051955] >ffff888005f29880: fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc
[ 86.051955] ^
[ 86.051955] ffff888005f29900: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
[ 86.051955] ffff888005f29980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
[ 86.051955] ==================================================================
root cause:
Just like the CVE-2021-3573, this bug occurs when a malicious user fakes a MCTP device and issues
sendmsg syscall when closing the device. By using userfaultfd, this bug can be stably triggered.
As the bug fix possibly self-explantory, please to refer to the above link for more details.
PoC code:
please see attachment.
=*=*=*=*=*=*=*=*= Credit =*=*=*=*=*=*=*=*=
Lin Ma (@f0rm2l1n) from ZheJiang University & Ant Group Light-Year Security Lab
Download attachment "attachment.zip" of type "application/zip" (7318 bytes)
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