What is the CVSS score of CVE-2024-36894?

CVE-2024-36894 has a CVSS 3.1 base score of 5.6 (Medium). CVSS vector: CVSS:3.1/AV:P/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H. EPSS exploitation probability: 0.0%.

Is there a patch available for CVE-2024-36894?

Yes, a patch is available for CVE-2024-36894. Update the affected software to the latest version immediately.

Linux Kernel CVE-2024-36894

MEDIUM

Race Condition (CWE-362)

2024-05-30 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Race Condition Information Disclosure Linux Linux Kernel

5.6

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

5.6 MEDIUM

AV:P/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:P/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H

Attack Vector

Physical

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

Lifecycle Timeline

CVE Published

May 30, 2024 - 16:15 cve.org

MEDIUM 5.6

DescriptionCVE.org

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

usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete

FFS based applications can utilize the aio_cancel() callback to dequeue pending USB requests submitted to the UDC. There is a scenario where the FFS application issues an AIO cancel call, while the UDC is handling a soft disconnect. For a DWC3 based implementation, the callstack looks like the following:

DWC3 Gadget FFS Application dwc3_gadget_soft_disconnect() ... --> dwc3_stop_active_transfers() --> dwc3_gadget_giveback(-ESHUTDOWN) --> ffs_epfile_async_io_complete() ffs_aio_cancel() --> usb_ep_free_request() --> usb_ep_dequeue()

There is currently no locking implemented between the AIO completion handler and AIO cancel, so the issue occurs if the completion routine is running in parallel to an AIO cancel call coming from the FFS application. As the completion call frees the USB request (io_data->req) the FFS application is also referencing it for the usb_ep_dequeue() call. This can lead to accessing a stale/hanging pointer.

commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") relocated the usb_ep_free_request() into ffs_epfile_async_io_complete(). However, in order to properly implement locking to mitigate this issue, the spinlock can't be added to ffs_epfile_async_io_complete(), as usb_ep_dequeue() (if successfully dequeuing a USB request) will call the function driver's completion handler in the same context. Hence, leading into a deadlock.

Fix this issue by moving the usb_ep_free_request() back to ffs_user_copy_worker(), and ensuring that it explicitly sets io_data->req to NULL after freeing it within the ffs->eps_lock. This resolves the race condition above, as the ffs_aio_cancel() routine will not continue attempting to dequeue a request that has already been freed, or the ffs_user_copy_work() not freeing the USB request until the AIO cancel is done referencing it.

This fix depends on commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently")

AnalysisAI

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete FFS based applications can utilize the aio_cancel(). Rated medium severity (CVSS 5.6).

Technical ContextAI

This vulnerability is classified under CWE-362. In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Fix race between aio_cancel() and AIO request complete FFS based applications can utilize the aio_cancel() callback to dequeue pending USB requests submitted to the UDC. There is a scenario where the FFS application issues an AIO cancel call, while the UDC is handling a soft disconnect. For a DWC3 based implementation, the callstack looks like the following: DWC3 Gadget FFS Application dwc3_gadget_soft_disconnect() ... --> dwc3_stop_active_transfers() --> dwc3_gadget_giveback(-ESHUTDOWN) --> ffs_epfile_async_io_complete() ffs_aio_cancel() --> usb_ep_free_request() --> usb_ep_dequeue() There is currently no locking implemented between the AIO completion handler and AIO cancel, so the issue occurs if the completion routine is running in parallel to an AIO cancel call coming from the FFS application. As the completion call frees the USB request (io_data->req) the FFS application is also referencing it for the usb_ep_dequeue() call. This can lead to accessing a stale/hanging pointer. commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") relocated the usb_ep_free_request() into ffs_epfile_async_io_complete(). However, in order to properly implement locking to mitigate this issue, the spinlock can't be added to ffs_epfile_async_io_complete(), as usb_ep_dequeue() (if successfully dequeuing a USB request) will call the function driver's completion handler in the same context. Hence, leading into a deadlock. Fix this issue by moving the usb_ep_free_request() back to ffs_user_copy_worker(), and ensuring that it explicitly sets io_data->req to NULL after freeing it within the ffs->eps_lock. This resolves the race condition above, as the ffs_aio_cancel() routine will not continue attempting to dequeue a request that has already been freed, or the ffs_user_copy_work() not freeing the USB request until the AIO cancel is done referencing it. This fix depends on commit b566d38857fc ("usb: gadget: f_fs: use io_data->status consistently") Affected products include: Linux Linux Kernel.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.