漏洞标题
cifs：修复cifs_demultiplex_thread()中的UAF问题。
漏洞描述信息
这段内容描述的是Linux内核中的一个UAF（Use After Free）漏洞。具体来说，cifsd进程在处理SMB2_negotiate请求时，存在未正确释放内存导致的UAF问题。
要重现这个漏洞，可以在相关代码段中增加延迟，使原本应该及时清理的内存未能被释放。
由于同步调用存在问题，而异步调用的回调在cifsd进程中执行，所以异步调用没有这个问题。
为了解决这个漏洞，可以在处理MID（Message Identifier）状态时添加一个额外的状态，标记MID状态为READY。这样，在唤醒等待者之前，可以确保获取响应是安全的。
CVSS信息
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
漏洞类别
释放后使用
漏洞标题
cifs: Fix UAF in cifs_demultiplex_thread()
漏洞描述信息
In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix UAF in cifs_demultiplex_thread()
There is a UAF when xfstests on cifs:
BUG: KASAN: use-after-free in smb2_is_network_name_deleted+0x27/0x160
Read of size 4 at addr ffff88810103fc08 by task cifsd/923
CPU: 1 PID: 923 Comm: cifsd Not tainted 6.1.0-rc4+ #45
...
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x44
print_report+0x171/0x472
kasan_report+0xad/0x130
kasan_check_range+0x145/0x1a0
smb2_is_network_name_deleted+0x27/0x160
cifs_demultiplex_thread.cold+0x172/0x5a4
kthread+0x165/0x1a0
ret_from_fork+0x1f/0x30
</TASK>
Allocated by task 923:
kasan_save_stack+0x1e/0x40
kasan_set_track+0x21/0x30
__kasan_slab_alloc+0x54/0x60
kmem_cache_alloc+0x147/0x320
mempool_alloc+0xe1/0x260
cifs_small_buf_get+0x24/0x60
allocate_buffers+0xa1/0x1c0
cifs_demultiplex_thread+0x199/0x10d0
kthread+0x165/0x1a0
ret_from_fork+0x1f/0x30
Freed by task 921:
kasan_save_stack+0x1e/0x40
kasan_set_track+0x21/0x30
kasan_save_free_info+0x2a/0x40
____kasan_slab_free+0x143/0x1b0
kmem_cache_free+0xe3/0x4d0
cifs_small_buf_release+0x29/0x90
SMB2_negotiate+0x8b7/0x1c60
smb2_negotiate+0x51/0x70
cifs_negotiate_protocol+0xf0/0x160
cifs_get_smb_ses+0x5fa/0x13c0
mount_get_conns+0x7a/0x750
cifs_mount+0x103/0xd00
cifs_smb3_do_mount+0x1dd/0xcb0
smb3_get_tree+0x1d5/0x300
vfs_get_tree+0x41/0xf0
path_mount+0x9b3/0xdd0
__x64_sys_mount+0x190/0x1d0
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
The UAF is because:
mount(pid: 921) | cifsd(pid: 923)
-------------------------------|-------------------------------
| cifs_demultiplex_thread
SMB2_negotiate |
cifs_send_recv |
compound_send_recv |
smb_send_rqst |
wait_for_response |
wait_event_state [1] |
| standard_receive3
| cifs_handle_standard
| handle_mid
| mid->resp_buf = buf; [2]
| dequeue_mid [3]
KILL the process [4] |
resp_iov[i].iov_base = buf |
free_rsp_buf [5] |
| is_network_name_deleted [6]
| callback
1. After send request to server, wait the response until
mid->mid_state != SUBMITTED;
2. Receive response from server, and set it to mid;
3. Set the mid state to RECEIVED;
4. Kill the process, the mid state already RECEIVED, get 0;
5. Handle and release the negotiate response;
6. UAF.
It can be easily reproduce with add some delay in [3] - [6].
Only sync call has the problem since async call's callback is
executed in cifsd process.
Add an extra state to mark the mid state to READY before wakeup the
waitter, then it can get the resp safely.
CVSS信息
N/A
漏洞类别
N/A
漏洞标题
Linux kernel 安全漏洞
漏洞描述信息
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于内存释放后重用。
CVSS信息
N/A
漏洞类别
其他