5.5 CVE-2021-47163

Patch

In the Linux kernel, the following vulnerability has been resolved: tipc: wait and exit until all work queues are done On some host, a crash could be triggered simply by repeating these commands several times: # modprobe tipc # tipc bearer enable media udp name UDP1 localip 127.0.0.1 # rmmod tipc [] BUG: unable to handle kernel paging request at ffffffffc096bb00 [] Workqueue: events 0xffffffffc096bb00 [] Call Trace: [] ? process_one_work+0x1a7/0x360 [] ? worker_thread+0x30/0x390 [] ? create_worker+0x1a0/0x1a0 [] ? kthread+0x116/0x130 [] ? kthread_flush_work_fn+0x10/0x10 [] ? ret_from_fork+0x35/0x40 When removing the TIPC module, the UDP tunnel sock will be delayed to release in a work queue as sock_release() can't be done in rtnl_lock(). If the work queue is schedule to run after the TIPC module is removed, kernel will crash as the work queue function cleanup_beareri() code no longer exists when trying to invoke it. To fix it, this patch introduce a member wq_count in tipc_net to track the numbers of work queues in schedule, and wait and exit until all work queues are done in tipc_exit_net().
https://nvd.nist.gov/vuln/detail/CVE-2021-47163

Categories

CWE-667 : Improper Locking
The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Use industry standard APIs to implement locking mechanism. Chain: improper locking (CWE-667) leads to race condition (CWE-362), as exploited in the wild per CISA KEV. Attacker provides invalid address to a memory-reading function, causing a mutex to be unlocked twice function in OS kernel unlocks a mutex that was not previously locked, causing a panic or overwrite of arbitrary memory. Chain: OS kernel does not properly handle a failure of a function call (CWE-755), leading to an unlock of a resource that was not locked (CWE-832), with resultant crash. OS kernel performs an unlock in some incorrect circumstances, leading to panic. OS deadlock OS deadlock involving 3 separate functions deadlock in library deadlock triggered by packets that force collisions in a routing table read/write deadlock between web server and script web server deadlock involving multiple listening connections multiple simultaneous calls to the same function trigger deadlock. chain: other weakness leads to NULL pointer dereference (CWE-476) or deadlock (CWE-833). deadlock when an operation is performed on a resource while it is being removed. Deadlock in device driver triggered by using file handle of a related device. Deadlock when large number of small messages cannot be processed quickly enough. OS kernel has deadlock triggered by a signal during a core dump. Race condition leads to deadlock. Chain: array index error (CWE-129) leads to deadlock (CWE-833) Program can not execute when attacker obtains a mutex. Program can not execute when attacker obtains a lock on a critical output file. Program can not execute when attacker obtains a lock on a critical output file. Critical file can be opened with exclusive read access by user, preventing application of security policy. Possibly related to improper permissions, large-window race condition. Chain: predictable file names used for locking, allowing attacker to create the lock beforehand. Resultant from permissions and randomness. Chain: Lock files with predictable names. Resultant from randomness. Product does not check if it can write to a log file, allowing attackers to avoid logging by accessing the file using an exclusive lock. Overlaps unchecked error condition. This is not quite CWE-412, but close.

References

416baaa9-dc9f-4396-8d5f-8c081fb06d67 Patch

https://git.kernel.org/stable/c/04c26faa51d1e2fe71cf13c45791f5174c37f986 Patch
https://git.kernel.org/stable/c/5195ec5e365a2a9331bfeb585b613a6e94f98dba Patch
https://git.kernel.org/stable/c/b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d Patch
https://git.kernel.org/stable/c/d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa Patch

af854a3a-2127-422b-91ae-364da2661108 Patch

https://git.kernel.org/stable/c/04c26faa51d1e2fe71cf13c45791f5174c37f986 Patch
https://git.kernel.org/stable/c/5195ec5e365a2a9331bfeb585b613a6e94f98dba Patch
https://git.kernel.org/stable/c/b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d Patch
https://git.kernel.org/stable/c/d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa Patch

CPE

cpe	start	end
Configuration 1
cpe:2.3:o:linux:linux_kernel::::::::	>= 4.1	< 5.4.124
cpe:2.3:o:linux:linux_kernel::::::::	>= 5.5	< 5.10.42
cpe:2.3:o:linux:linux_kernel::::::::	>= 5.11	< 5.12.9
cpe:2.3:o:linux:linux_kernel:5.13:rc1::::::
cpe:2.3:o:linux:linux_kernel:5.13:rc2::::::
cpe:2.3:o:linux:linux_kernel:5.13:rc3::::::

REMEDIATION

Patch

Url
https://git.kernel.org/stable/c/04c26faa51d1e2fe71cf13c45791f5174c37f986
https://git.kernel.org/stable/c/5195ec5e365a2a9331bfeb585b613a6e94f98dba
https://git.kernel.org/stable/c/b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d
https://git.kernel.org/stable/c/d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa
https://git.kernel.org/stable/c/04c26faa51d1e2fe71cf13c45791f5174c37f986
https://git.kernel.org/stable/c/5195ec5e365a2a9331bfeb585b613a6e94f98dba
https://git.kernel.org/stable/c/b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d
https://git.kernel.org/stable/c/d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa

EXPLOITS

Exploit-db.com

id	description	date
No known exploits

POC Github

Url
No known exploits

Other Nist (github, ...)

Url
No known exploits

CAPEC

Common Attack Pattern Enumerations and Classifications

id	description	severity
25	Forced Deadlock The adversary triggers and exploits a deadlock condition in the target software to cause a denial of service. A deadlock can occur when two or more competing actions are waiting for each other to finish, and thus neither ever does. Deadlock conditions can be difficult to detect. The adversary initiates an exploratory phase to get familiar with the system. The adversary triggers a first action (such as holding a resource) and initiates a second action which will wait for the first one to finish. If the target program has a deadlock condition, the program waits indefinitely resulting in a denial of service.	High
26	Leveraging Race Conditions The adversary targets a race condition occurring when multiple processes access and manipulate the same resource concurrently, and the outcome of the execution depends on the particular order in which the access takes place. The adversary can leverage a race condition by "running the race", modifying the resource and modifying the normal execution flow. For instance, a race condition can occur while accessing a file: the adversary can trick the system by replacing the original file with their version and cause the system to read the malicious file. The adversary explores to gauge what level of access they have. The adversary gains access to a resource on the target host. The adversary modifies the targeted resource. The resource's value is used to determine the next normal execution action. The resource is modified/checked concurrently by multiple processes. By using one of the processes, the adversary is able to modify the value just before it is consumed by a different process. A race condition occurs and is exploited by the adversary to abuse the target host.	High
27	Leveraging Race Conditions via Symbolic Links This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to them. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file they will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file. [Verify that target host's platform supports symbolic links.] This attack pattern is only applicable on platforms that support symbolic links. [Examine application's file I/O behavior] Analyze the application's file I/O behavior to determine where it stores files, as well as the operations it performs to read/write files. [Verify ability to write to filesystem] The attacker verifies ability to write to the target host's file system. [Replace file with a symlink to a sensitive system file.] Between the time that the application checks to see if a file exists (or if the user has access to it) and the time the application actually opens the file, the attacker replaces the file with a symlink to a sensitive system file.	High

MITRE

Techniques

id	description
T1499.004	Endpoint Denial of Service: Application or System Exploitation
© 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

Mitigations

id	description
M1037	Leverage services provided by Content Delivery Networks (CDN) or providers specializing in DoS mitigations to filter traffic upstream from services. Filter boundary traffic by blocking source addresses sourcing the attack, blocking ports that are being targeted, or blocking protocols being used for transport.
© 2022 The MITRE Corporation. Esta obra se reproduce y distribuye con el permiso de The MITRE Corporation.

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