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CVE-2024-41050

Disclosure Date: July 29, 2024 •
CVE-2024-41050
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Description

In the Linux kernel, the following vulnerability has been resolved:

cachefiles: cyclic allocation of msg_id to avoid reuse

Reusing the msg_id after a maliciously completed reopen request may cause
a read request to remain unprocessed and result in a hung, as shown below:

   t1       |      t2       |      t3

cachefiles_ondemand_select_req
cachefiles_ondemand_object_is_close(A)
cachefiles_ondemand_set_object_reopening(A)
queue_work(fscache_object_wq, &info->work)

            ondemand_object_worker
             cachefiles_ondemand_init_object(A)
              cachefiles_ondemand_send_req(OPEN)
                // get msg_id 6
                wait_for_completion(&req_A->done)

cachefiles_ondemand_daemon_read
// read msg_id 6 req_A
cachefiles_ondemand_get_fd
copy_to_user

                            // Malicious completion msg_id 6
                            copen 6,-1
                            cachefiles_ondemand_copen
                             complete(&req_A->done)
                             // will not set the object to close
                             // because ondemand_id && fd is valid.

            // ondemand_object_worker() is done
            // but the object is still reopening.

                            // new open req_B
                            cachefiles_ondemand_init_object(B)
                             cachefiles_ondemand_send_req(OPEN)
                             // reuse msg_id 6

process_open_req
copen 6,A.size
// The expected failed copen was executed successfully

Expect copen to fail, and when it does, it closes fd, which sets the
object to close, and then close triggers reopen again. However, due to
msg_id reuse resulting in a successful copen, the anonymous fd is not
closed until the daemon exits. Therefore read requests waiting for reopen
to complete may trigger hung task.

To avoid this issue, allocate the msg_id cyclically to avoid reusing the
msg_id for a very short duration of time.

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CVSS V3 Severity and Metrics
Base Score:
None
Impact Score:
Unknown
Exploitability Score:
Unknown
Vector:
Unknown
Attack Vector (AV):
Unknown
Attack Complexity (AC):
Unknown
Privileges Required (PR):
Unknown
User Interaction (UI):
Unknown
Scope (S):
Unknown
Confidentiality (C):
Unknown
Integrity (I):
Unknown
Availability (A):
Unknown

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux 35710c6c4a1c
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • Linux

Products

  • Linux
Technical Analysis