CVE-2025-40315
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BaseFortify

Publication date: 2025-12-08

Last updated on: 2025-12-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Fix epfile null pointer access after ep enable. A race condition occurs when ffs_func_eps_enable() runs concurrently with ffs_data_reset(). The ffs_data_clear() called in ffs_data_reset() sets ffs->epfiles to NULL before resetting ffs->eps_count to 0, leading to a NULL pointer dereference when accessing epfile->ep in ffs_func_eps_enable() after successful usb_ep_enable(). The ffs->epfiles pointer is set to NULL in both ffs_data_clear() and ffs_data_close() functions, and its modification is protected by the spinlock ffs->eps_lock. And the whole ffs_func_eps_enable() function is also protected by ffs->eps_lock. Thus, add NULL pointer handling for ffs->epfiles in the ffs_func_eps_enable() function to fix issues
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Meta Information
Published
2025-12-08
Last Modified
2025-12-08
Generated
2026-05-07
AI Q&A
2025-12-10
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40315
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
What immediate steps should I take to mitigate this vulnerability?

Apply the patch or update to a Linux kernel version that includes the fix for the race condition in the usb gadget f_fs driver, specifically the fix for epfile null pointer access after ep enable. This involves ensuring that the kernel version you are running has the updated ffs_func_eps_enable() function with NULL pointer handling for ffs->epfiles. Until patched, avoid running vulnerable kernel versions or disable the affected USB gadget functionality if possible.


Can you explain this vulnerability to me?

This vulnerability is a race condition in the Linux kernel's USB gadget function (f_fs). Specifically, when the function ffs_func_eps_enable() runs at the same time as ffs_data_reset(), a NULL pointer dereference can occur. This happens because ffs_data_clear(), called by ffs_data_reset(), sets a pointer (ffs->epfiles) to NULL before resetting a count, leading to an attempt to access a NULL pointer in ffs_func_eps_enable(). The issue was fixed by adding NULL pointer handling in ffs_func_eps_enable().


How can this vulnerability impact me? :

This vulnerability can cause a NULL pointer dereference in the Linux kernel, which may lead to a kernel crash or system instability when USB gadget functions are used. This could result in denial of service or unexpected behavior on affected systems.


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